U.S. patent application number 13/269251 was filed with the patent office on 2012-11-22 for method and system of ventilation for a healthy home configured for efficient energy usage and conservation of energy resources.
This patent application is currently assigned to PVT Solar, Inc.. Invention is credited to Ramachandran NARAYANAMURTHY, Joshua R. Plaisted.
Application Number | 20120295534 13/269251 |
Document ID | / |
Family ID | 44560439 |
Filed Date | 2012-11-22 |
United States Patent
Application |
20120295534 |
Kind Code |
A1 |
NARAYANAMURTHY; Ramachandran ;
et al. |
November 22, 2012 |
METHOD AND SYSTEM OF VENTILATION FOR A HEALTHY HOME CONFIGURED FOR
EFFICIENT ENERGY USAGE AND CONSERVATION OF ENERGY RESOURCES
Abstract
A method for providing a ventilation control compliant with an
adopted ventilation standard for efficient energy usage and
conservation of energy resources. The method includes operating a
home energy system to generate solar energy within a daily active
period and draw ambient fresh air, and setting a daily ventilation
period as a fractional period of a day. The daily ventilation
period is substantially coordinated with the daily active period
during a heating/cooling period for the home. Additionally, the
method includes determining a target volume in compliance with the
adopted ventilation standard and determining a flow rate for
delivering the fresh air during the daily ventilation period.
Moreover, the method includes monitoring an accumulated total
ventilation volume of the delivered fresh air until the accumulated
total ventilation volume is within a vicinity of a target
volume.
Inventors: |
NARAYANAMURTHY; Ramachandran;
(EI Cerrito, CA) ; Plaisted; Joshua R.; (Oakland,
CA) |
Assignee: |
PVT Solar, Inc.
Fremont
CA
|
Family ID: |
44560439 |
Appl. No.: |
13/269251 |
Filed: |
October 7, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13108626 |
May 16, 2011 |
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13269251 |
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Current U.S.
Class: |
454/256 |
Current CPC
Class: |
F24F 11/30 20180101;
F24F 2110/10 20180101; F24F 3/14 20130101; F24F 2110/20
20180101 |
Class at
Publication: |
454/256 |
International
Class: |
F24F 7/00 20060101
F24F007/00 |
Claims
1. An apparatus for providing fresh air flow into a home for
efficient energy usage and conservation of energy resources, the
apparatus comprising: a solar module associated with a building
structure, the solar module being configured for producing thermal
energy from a solar energy source during a first period of time
daily; an air plenum structure configured with the solar module to
draw fresh air from an ambient region and to transfer the fresh air
to an inner space of the building structure during a second period
of time daily; an energy transfer module coupled between the air
plenum structure and the inner space of the building structure and
configured to process and transfer the fresh air from the ambient
region; and a control module configured to operate the energy
transfer module to deliver the fresh air into the inner space of
the building structure within the second period of time to achieve
a predetermined ventilation standard for the building structure and
configured to maintain a substantially constant heating load or a
substantially constant cooling load within the inner space of the
building structure during the second period of time, the second
period of time being associated with the first period of time for
utilizing the thermal energy carried by the fresh air.
2. The apparatus of claim 1 wherein the second period of time is
either substantially within the first period of time to transfer
the fresh air carrying thermal energy produced by the solar module
to the inner space of the building structure, or substantially
after an end of the first period of time and before a start of the
first period of time next day to transfer the fresh air cooled by
the solar module via radiation to the inner space of the building
structure.
3. The apparatus of claim 1 wherein the building structure is a
residential home and the predetermined ventilation standard is
ASHRAE standard 62.2 used for meeting building energy codes.
4. The apparatus of claim 1 wherein the energy transfer module
comprises a blower, a damper coupled to the blower, a duct
configured with the inner space or an exhaust port, and one or more
sensors disposed in an upstream region and a downstream region
communicating with the blower.
5. The apparatus of claim 4 wherein the control module comprises a
computer readable memory, the computer readable memory including a
first code directed to determine a flow rate to drive the fresh
air, a second code directed to adjust the damper to direct the
fresh air into the inner space or exhaust, a third code directed to
receive information from the one or more sensors to determine a
volume of the fresh air passing through within a selected period of
time.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] NOT APPLICABLE
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED
RESEARCH AND DEVELOPMENT
[0002] NOT APPLICABLE
REFERENCE TO A "SEQUENCE LISTING," A TABLE, OR A COMPUTER PROGRAM
LISTING APPENDIX SUBMITTED ON A COMPACT DISK
[0003] NOT APPLICABLE
BACKGROUND OF THE INVENTION
[0004] The present invention relates to operations of a home energy
system. More particularly, the present invention provides a method
and related system for providing daily home ventilation compliant
with the ASHRAE 62.2 standard. Merely, by way of example, the
present invention has been applied to integrate daily home
ventilation control in association with an operation of the home
energy system for utilizing solar thermal energy to provide space
heating and space cooling for the home with up to 80% energy usage
saving for home ventilation, but it would be recognized that the
invention has a much broader range of applications.
[0005] Over the past centuries, the world population of human
beings has exploded. Along with the population, demand for
resources has also grown explosively. Such resources include raw
materials such as wood, iron, and copper and energy, such as fossil
fuels, including coal and oil. Industrial countries worldwide
project more increases in oil consumption for transportation and
heating purposes from developing nations such as China and India.
Obviously, our daily lives depend, for the most part, upon oil or
other forms of fossil fuel, which are becoming scarce as it becomes
depleted.
[0006] Along with the depletion of our fossil fuel resources, our
planet has experienced a global warming phenomena, known as "global
warming," and brought to our foremost attention by our former Vice
President Al Gore. Global warming is known as an increase in an
average temperature of the Earth's air near its surface, which is
projected to continue at a rapid pace. Warming is believed to be
caused by greenhouse cases, which are derived, in part, from use of
fossil fuels. The increase in temperature is expected to cause
extreme weather conditions and a drastic size reduction of the
polar ice caps, which in turn will lead to higher sea levels and an
increase in the rate of warming. Ultimately, other effects include
mass species extinctions, and possibly other uncertainties that may
be detrimental to human beings.
[0007] Much if not all of the useful energy found on the Earth
comes from our sun. Generally all common plant life on the Earth
achieves life using photosynthesis processes from sun light. Fossil
fuels such as oil were also developed from biological materials
derived from energy associated with the sun. For life on the planet
Earth, the sun has been our most important energy source and fuel
for modern day solar energy. Solar energy possesses many
characteristics that are very desirable! Solar energy is renewable,
clean, abundant, and often widespread. Accordingly, solar panels
have been developed to convert sunlight into energy. Most solar
energy systems today use "PV" technology. They convert sunlight
directly into the electricity that you use to light your home, or
power your appliances. As merely another example, solar thermal
panels also are developed to convert electromagnetic radiation from
the sun into thermal energy for heating homes, running certain
industrial processes, or driving high grade turbines to generate
electricity. In fact, solar photovoltaic panels also generate heat
as a side product. Solar panels are generally composed of an array
of solar (PV and/or thermal) cells, which are interconnected to
each other. The cells are often arranged in series and/or parallel
groups of cells in series. Accordingly, solar panels have great
potential to benefit our nation, security, and human users. They
can even diversify our energy requirements and reduce the world's
dependence on oil and other potentially detrimental sources of
energy.
[0008] Although solar panels have been used successful for certain
applications, there are still certain limitations. Solar cells are
often costly. Depending upon the geographic region, there are often
financial subsidies from governmental entities for purchasing solar
panels, which often cannot compete with the direct purchase of
electricity from public power companies. Additionally, most PV
solar energy systems only utilize about 15% of the captured sun's
energy. The remaining energy, mostly in the form of thermal energy,
remains untapped. Moreover, conventional solar energy systems are
also difficult to maintain and monitor for operational accuracy.
Once a solar energy system has been installed, there is simply no
easy way to monitor the accuracy of energy production. In
particular, a healthy home system is provided to operate an energy
transfer module coupled to other traditional building utility
modules to deliver solar thermal energy converted from both PV
solar panels and solar thermal panels for home utility applications
such as electricity supply, water heating, home heating, home
cooling, and ventilation, there is no existing method to set or
program the control setting for automatically adjusting building
comfort in terms of heating, cooling, and ventilation for
maximizing the utilization efficiency of the captured solar energy.
These and other limitations are described throughout the present
specification, and may be described in more detail below.
[0009] From the above, it is seen that techniques for improving
operation of an integrated solar energy system are highly
desired.
BRIEF SUMMARY OF THE INVENTION
[0010] The present invention relates to operation of a home energy
system. More particularly, the present invention provides a method
for providing home ventilation compliant with an adopted ASHRAE
standard 62.2 by implementing a ventilation logic in the system
control program without adding additional mechanical equipments.
Merely, by way of example, the present invention has been applied
to perform daily home ventilation control integrated with an
operation of the home energy system for utilizing solar thermal
energy to provide space heating and space cooling to coordinate
with the home ventilation, but it would be recognized that the
invention has a much broader range of applications.
[0011] In an embodiment, the present invention provides an
apparatus for providing fresh air flow into a home for efficient
energy usage and conservation of energy resources. The apparatus
includes a solar module associated with a building structure. The
solar module is configured for producing thermal energy from a
solar energy source during a first period of time daily. The
apparatus further includes an air plenum structure configured with
the solar module to draw fresh air from an ambient region and to
transfer the fresh air to an inner space of the building structure
during a second period of time daily. Additionally, the apparatus
includes an energy transfer module coupled between the air plenum
structure and the inner space of the building structure and
configured to process and transfer the fresh air from the ambient
region. Moreover, the apparatus includes a control module
configured to operate the energy transfer module to deliver the
fresh air into the inner space of the building structure within the
second period of time to achieve a predetermined ventilation
standard for the building structure and configured to maintain a
substantially constant heating load or a substantially constant
cooling load within the inner space of the building structure
during the second period of time. The second period of time is
associated with the first period of time for utilizing the thermal
energy carried by the fresh air. In a specific embodiment, the
energy transfer module includes at least a blower, a damper coupled
to the blower, a duct configured with the inner space or an exhaust
port, and one or more sensors disposed in an upstream region and a
downstream region communicating with the blower. The control module
further includes a computer readable memory. The computer readable
memory includes a first code directed to determine a flow rate to
drive the fresh air, a second code directed to adjust the damper to
direct the fresh air into the inner space or exhaust, a third code
directed to receive information from the one or more sensors to
determine a volume of the fresh air passing through within a
selected period of time.
[0012] In an alternative embodiment, the present invention provides
a method for providing a ventilation control compliant with an
adopted ventilation standard for efficient energy usage and
conservation of energy resources. The method includes operating a
home energy system to utilize solar energy within an active period
and draw fresh air for providing either space heating or space
cooling for a home respectively in a heating period or a cooling
period. The method further includes setting a daily ventilation
period as a fractional period of a day. The daily ventilation
period is substantially coincident with the daily active period
during a heating period for the home or a time period after the
daily active period during a cooling period for the home.
Additionally, the method includes determining a target volume in
compliance with a ventilation standard and determining a flow rate
for delivering the fresh air during the daily ventilation period.
Furthermore, the method includes performing ventilation in the
daily ventilation period to deliver the fresh air to an inner
region of the home using the flow rate. Moreover, the method
includes monitoring an accumulated total ventilation volume of the
delivered fresh air until the accumulated total ventilation volume
is within a vicinity of the target volume. In an specific
embodiment, the method includes providing ventilation by delivering
the fresh air carrying the solar thermal energy within the daily
ventilation period for heating the inner region of the home during
the heating period for the home, thereby providing saving up to 60%
in energy usage and equipment cost for providing space heating
required by home comfort setting compared to delivering the fresh
air full day. In another specific embodiment, the method includes
performing ventilation by delivering the fresh air cooled by
radiation from the solar module to the inner region of the home
within the daily ventilation period for providing flush cooling
during the cooling period for the home, thereby providing saving up
to 60% in energy usage and equipment cost for providing space
cooling required by home comfort setting compared to delivering the
fresh air full day.
[0013] In an specific embodiment, the present invention provides a
method of a daily home ventilation control compliant with ASHRAE
standard 62.2 for efficient energy usage and conservation of energy
resources. The method includes operating a system for providing
fresh air into an interior region of a building structure. The
system including at least an energy transfer module coupled to a
solar thermal module. The method further includes delivering a flow
of the fresh air collected by the solar thermal module from an
ambient region through the energy transfer module into the interior
region of the building structure to provide ventilation of the
interior region of the building structure. Additionally, the method
includes calculating an integrated volume of the flow within a
15-minute runtime continuously for a day to record in a float data
table. The method further includes determining a target volume
compliant with the ASHRAE standard 62.2 for ventilation within a
daily ventilation period based on an intermittent rate for
delivering the flow of the fresh air. The daily ventilation period
is a partial period of a day in association with an active period
when solar energy is generated by the solar thermal module for
heating the fresh air or a time period after the active period when
radiation cooling is provided for cooling the fresh air. The active
period begins at a start time and ends at an end time. Then, the
method includes determining if the system is set in a heating mode
or a cooling mode at the start time. If the system is determined to
be set in the heating mode at the start time, the method executing
the following steps for beginning the daily ventilation period from
the start time to deliver the flow of the fresh air at the
intermittent rate or a first flow rate, for calculating an
accumulated ventilation volume based on the float data table from
the start time up to a current time, and for determining if the
accumulated ventilation volume is smaller than the daily
ventilation target volume. Furthermore, the method includes
performing ventilation in the daily ventilation period with at
least the intermittent rate if the accumulated ventilation volume
is determined to be smaller than the daily ventilation target
volume, or cutting off ventilation if the accumulated ventilation
volume is determined to be no smaller than the daily ventilation
target volume or if the current time reaches the end time. If the
system is determined to be set in the cooling mode at the start
time, the method executing the following steps for keeping the
system in the cooling mode until a predetermined time after the end
time to begin the daily ventilation period to deliver the flow of
the fresh air at the intermittent rate or a second flow rate, for
calculating an accumulated ventilation volume based on the float
data table from a start of the daily ventilation period up to a
current time, for determining if the accumulated ventilation volume
is smaller than the daily ventilation target volume. Moreover, the
method includes performing ventilation in the daily ventilation
period with at least the intermittent rate if the accumulated
ventilation volume is determined to be smaller than the daily
ventilation target volume, or cutting off ventilation if the
accumulated ventilation volume is determined to be no smaller than
the daily ventilation target volume or if the current time reaches
the start time of a next active period. In a specific embodiment,
if the accumulated ventilation volume is determined to be smaller
than the daily target ventilation volume, the method executes the
following steps respectively to deliver the flow of the fresh air
using the intermittent rate if the system is set in the heating
mode but not operated to provide space heating and an interior
temperature is detected to be lower than an upper bound of a
comfort setting, to deliver the flow of the fresh air using the
first flow rate by the system operated to provide space heating, to
deliver the flow of the fresh air using the intermittent rate if
the system is set in the cooling mode but not operated to provide
space cooling and an interior temperature is detected to be higher
than a lower bound of a comfort setting, and to deliver the flow of
the fresh air using the second flow rate by the system operated to
provide space cooling. The first flow rate is greater than the
intermittent rate the second flow rate is greater than the
intermittent rate.
[0014] Still further, the present invention provides a method for
performing ventilation using the base rate for 1 hour if it is
determined that there has not been ventilation to the home in the
past 11 hours based on the daily float data table. In yet another
embodiment, the present invention still provides a ventilation
method for performing a full-day ventilation using a fixed flow
rate equal to a base rate compliant with the ASHRAH standard 62.2.
Of course, there can be other variations, modifications, and
alternatives.
[0015] Many benefits are achieved by way of the present invention
over conventional techniques. For example, the present technique
provides an easy way to implement a home ventilation operation
using an integrated home energy system. One or more embodiments
provide a method for performing intermittent ventilation in a
specified ventilation period that can be substantially shorter than
a full day 24 hours time and having achieved a ventilation result
compliant with states adopted ventilation standard such as ASHRAE
standard 62.2 and the likes for a healthy residential home. The
method adds a level of ventilation control logic within a system
controller configured to operate the home energy system for
providing native space heating or space cooling to coordinate with
the home ventilation and other utility applications. Additionally,
the method provides an economic ventilation process that takes
advantage of the native system operation for providing space
heating and space cooling by associating the daily ventilation
period to the system active period to utilize solar energy. This
allows home owner who chooses the home energy system provided
according to this invention for utilizing solar energy in home
utility applications without need of adding extra mechanical
equipments for ventilation, instead, with options for reducing the
size of heating equipment and air conditioner. This method further
avoids paying high energy penalty to force the system to deliver
hot air into the home in cooling season or cold air into the home
under space heating in a heating season, instead of using
coordination of the ventilation with the native space heating and
space cooling to have substantially free ventilation. In a
preferred embodiment, the present method and system provides for
fresh air within a home without additional cooling or heating loads
or the like, which leads to increased use of energy. That is, fresh
air is provided without additional energy or with less energy use.
The embodiments of the invention allow 60% or more saving of energy
usage for home ventilation comparing to conventional methods. In
another preferred embodiment, the present method and system
provides for fresh air within a home without introducing additional
dusts, particles, and moistures that will affect the air quality
within the interior space of the home. Depending upon the
embodiment, one or more of these benefits may be achieved. These
and other benefits will be described in more detail throughout the
present specification and more particularly below.
[0016] Various additional objects, features and advantages of the
present invention can be more fully appreciated with reference to
the detailed description and accompanying drawings that follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a simplified block diagram of a home energy system
according to an embodiment of the present invention;
[0018] FIG. 2 is a simplified flow diagram illustrating a method
for providing daily ventilation for a healthy home in association
with a home energy system according to an embodiment of the present
invention;
[0019] FIG. 3 is an exemplary diagram illustrating a daily
ventilation rate plot for a home according to an embodiment of the
present invention;
[0020] FIG. 4 is an exemplary diagram illustrating a daily
ventilation volume plot for a home according to an embodiment of
the present invention; and
[0021] FIGS. 5A-5D are simplified flow diagrams illustrating a
method for providing daily home ventilation for a healthy home in
association with a home energy system according to a specific
embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The present invention relates to operation of a home energy
system. More particularly, the present invention provides a method
for providing daily home ventilation compliant with ASHRAE standard
62.2 and the likes by implementing a ventilation logic on the
system control program without adding additional mechanical
equipments. Merely, by way of example, the present invention has
been applied to a healthy home in association with a home energy
system configured to utilize solar energy for providing space
heating/cooling coordinated with home ventilation to achieve
substantially efficient energy usage and conservation of energy
resources, but it would be recognized that the invention has a much
broader range of applications.
[0023] FIG. 1 is a simplified block diagram of a home energy system
for a healthy home according to an embodiment of the present
invention. This diagram is merely an example, which should not
unduly limit the scope of the claims herein. One of ordinary skill
in the art would recognize other variations, modifications, and
alternatives. It is also understood that the examples and
embodiments described herein are for illustrative purposes only and
that various modifications or changes in light thereof will be
suggested to persons skilled in the art and are to be included
within the spirit and purview of this process and scope of the
appended claims.
[0024] As shown, the home energy system 100 (or simply stated as
"the system" in the context) is installed in association with a
home dwelling or a building structure 101 for providing ventilation
in addition to supplying solar thermal energy for other home
utility applications. The system 100 includes a system controller
140 to control an energy transfer module 120 for utilizing both
electrical and thermal energy converted from solar energy of sun 10
by a solar module 110 installed on a roof of the building structure
101. In particular, the solar module 110 is a solar thermal module
converting solar energy directly to thermal energy or a PV module
providing thermal energy as a side product or a combination of
both. The system 100 includes a plenum structure 115 directly
located underneath a bottom face of the solar module 110. The
plenum structure 115 is configured to draw fresh air 111 from
ambient passing across the whole bottom face of the solar module
110 to carry at least partially the thermal energy generated by the
solar module 110. The fresh air 111 is guided into the energy
transfer module 120 via an air inlet 121.
[0025] In a specific embodiment, the system controller 140 is
configured to monitor the operation of the solar module 110 with an
active period for generating thermal energy (and electrical power
too) from solar energy and a controlled delivery of the a flow of
the fresh air through the plenum structure 115 in a coordinated
manner, depending on whether the system is set in a heating or
cooling mode. When the system 100 is set in heating mode and the
solar module 110 actively runs to generate thermal energy, the flow
of the fresh air 111 collected in the plenum structure 115 will be
heated therein and can be delivered to an interior space 106 of the
building structure 101 for providing both space heating and
ventilation. When the system 100 is set in the cooling mode, during
the active period the flow of the fresh air 111 that is heated can
be directed to an exhaust port instead of being delivered into the
interior space 106. While after the active period (most likely the
night time) the flow of the fresh air 111 may be cooled by the
solar module 110 via a radiation cooling effect and is delivered
into the interior space of the building structure to cause space
cooling and provide ventilation. In multiple aspects of the system
applications, the flow of the fresh air 111 can be processed in the
energy transfer module 120 under the control of the system
controller 140 and utilized by the system to at least provide space
heating, space cooling, as well as ventilation for the interior
space region 106 of the building structure 101. Of course, there
are many variations, alternatives, and modifications.
[0026] Referring to FIG. 1, the energy transfer module 120 includes
a blower 125 run for adjusting a flow rate of the air therein and
driving the air toward several outlets 122 and 123. One outlet 123
is used for exhausting the flow back to outside of the building
structure via an exhaust port when the system controller 140
determines that there is no need for home space heating, space
cooling, or ventilation. The outlet 122 is configured to
specifically deliver a flow 161 of the fresh air into interior
zones 106 of the home 101, which may carry heating or cooling power
for space heating or space cooling, or additionally be used for
ventilation. Two dampers 128 and 129 are respectively disposed in
the two outlets 122 and 123 and also are controlled by the system
controller 140 to adjust the flow volume passed into each outlet.
The energy transfer module 120 also includes one or more sensors
171, 172 respectively disposed in the upstream regions and
downstream regions communicating with the blower 125 to collect
temperature, pressure, flow rate information and send to the system
controller 140 via communication path 142. The system controller
140 can use the information to calculate an accumulated flow volume
during a certain runtime window whenever the blower 125 operates
and the damper 128 or 129 is open.
[0027] In one or more embodiments, the system controller 140 is
configured to communicate via a channel 145 with a thermostat 150,
which is disposed at an interior space 106 of the building
structure 101 and is programmed on multiple modes of operation to
provide home comfort based on seasoning necessities and occupancy
schedules. For example, an indoor comfort band can be set at
between a high setpoint T_zone_max and a low setpoint T_zone_min.
The thermostat 150 can choose to set the system 100 in a "Heat"
mode or a "Cool" mode, or can be turned off ("Off" mode). The
thermostat 150 includes a built-in temperature sensor that can
measure a current indoor temperature T_zone and pass the
information to the system controller 140 to reset the system 100
from a heating mode to a cooling mode. In case of "Off" mode (or
the thermostat is not installed at all), the system controller 140
can rely on a measured ambient temperature T_ambient to compare
with a pre-specified temperature value determine whether the system
should be set to a heating mode or a cooling mode. For example, if
T_ambient<15 C..degree., the system is determined to be set in a
heating mode to provide necessary home comfort.
[0028] In another embodiment, the system controller 140 sends the
indoor condition information collected from the thermostat 150 via
the communication channel 142 back to the energy transfer module
120. Accordingly, the energy transfer module 120 at least operates
the blower 125 and the dampers 128 or 129 to control the timing and
volume of the delivered airflow 161 into the interior region 106.
In a specific embodiment, the energy transfer module 120 includes a
number of sensors 171 and 172 that can measure the inlet/outlet
temperatures and pressures for the system controller 140 to
determine the mass flow through the energy transfer module 120. For
example, whenever the blower 125 is running and the damper 128 is
open the volume of the airflow 161 can be calculated and recorded
over time. Of course, there are many variations, alternatives, and
modifications.
[0029] In a preferred embodiment, the present invention provide an
additional logic level to the operation control of the system 100
for providing mechanical ventilation for the healthy home energy
system operated for providing space heating/cooling. The
ventilation is required to be in compliance with an emerging
national standard on home ventilation based on the ASHRAE standard
62.2. The advantage of the system for providing ventilation in
association with providing space heating/cooling is to avoid costly
options for homeowners to add additional mechanical equipments and
controls. ASHRAE standard 62.2 defines the roles of and minimum
requirements for mechanical and natural ventilation systems
associated with the building envelope to provide acceptable indoor
air quality in residential homes or low-rise building structures.
The acceptable indoor air quality in this standard focuses mainly
on chemical, physical, and biological substances, not the thermal
comfort requirements. In a simplified aspect of this standard, to
provide acceptable indoor air quality is translated to provide
proper home ventilation by transferring fresh air (assuming no
dust, contamination, or properly filtered) from outdoor ambient to
interior zones of the building structure with a desired ventilation
rate and properly exhausting poor quality indoor air out. In most
cases for typical residential home and low-rise building
structures, natural ventilation only is not able to satisfy the
ASHRAE standard 62.2 requirement and usage of mechanical
ventilation in an active airflow process involving motor-driven fan
and blower is needed. Of course, embodiments of the present
invention do not limit the scope of the claims herein for just
satisfying the ASHRAE standard 62.2. The ventilation logic can be
applied in compliance with other ventilation standard adopted for
residential home in other states or regions (such as Europe, Japan,
China) and standards for ventilation in industrial or public
buildings.
[0030] According to the ventilation standard set in the ASHRAE
standard 62.2, a base ventilation rate for an operating blower can
be determined in a 24 hours/day process for performing the
whole-building ventilation to bring in outdoor air continuously,
depending on a floor area of the specific building and number of
bedrooms. Table 1 shows a general input data
TABLE-US-00001 TABLE 1 Config.dat Variable Type Units Description
IAQ_Ventilation_enable Binary -- A flag as to whether or not the
controller should enable the ASHRAE 62.2 logic House_area Float
m.sup.2 Floor footprint of house House_stories Int -- Number of
stories used to calculate home volume. Bedroom_count Int -- Number
of bedrooms in home. Used to calculate ASHRAEventilation rate
required for activating a ventilation control logic within a system
operation control settings for native space heating or cooling. The
parameter IAQ_ventilation_enable is binary data as a flag on
whether or not the controller should enable the ASHRAE 62.2
ventilation logic. Other parameters like the house area, stories,
and bedroom count are related to a specific building structure for
implementing the method in the associated with a home energy
system. These parameters are inputted and saved in the system
controller memory as a Config.dat file. The base ventilation rate
based on full-day constant ventilation can be calculated from the
Config.dat parameters as:
V base = 0.1 .times. House area + 7.5 .times. ( Bedroom count + 1 )
2119 ( Eq . 1 ) ##EQU00001##
As an example, a 200 m.sup.2 (2,000 ft.sup.2) home with 3 bedrooms
would have a base ventilation rate of 0.024 m.sup.3/s (50 CFM),
V base = 0.1 .times. 200 + 7.5 .times. ( 3 + 1 ) 2119 = 0.024 m 3 /
s . ( Eq . 2 ) ##EQU00002##
[0031] However, the ASHRAE standard 62.2 also allows an alternative
way of ventilation by operating a whole-building mechanical
ventilation system intermittently, e.g., within a partial period
daily if the ventilation rate can be adjusted instead of using a
fixed V.sub.base. In a specific embodiment, the present invention
provides a method to control the blower 125 of the energy transfer
module 120 in the system 100 as an intermittent ventilation system
to be operated with an increased intermittent ventilation rate over
the base rate in a time period shorter than 24 hours per day, while
keeping a total daily integrated ventilation volume in compliance
with the ASHRAE standard 62.2. In an implementation, whenever the
blower 125 is running and the damper 128 is open the system
controller 140 is configured to control the energy transfer module
120 to collect multiple sensor information about the flow 161 that
passes into the interior space 106 of the building structure 101.
In a specific embodiment, an accumulated airflow volume over any
15-minute time period can be measured and recorded in a float data
table in the system controller 140 Table 2 shows a float data file
about the total airflow volume delivered to the
TABLE-US-00002 TABLE 2 15-Minute Performance Data Table Variable
Type Units Description V_ventilation float m.sup.3 Total airflow
volume delivered over 15-min. timestep.
building structure over any daily 15-minute timestep obtained by
the energy transfer module 120. This operation can be embedded in
the system control program no matter the whole system is set and
operated in a heating mode or a cooling mode or any time during the
day. The 15-minute performance data can be collected and stored
continuously in system controller memory with at least the data in
the past 24 hours being kept and available for retriving.
[0032] Because intermittent ventilation is not as effective as
continuos ventilation, an `effectiveness` factor is deployed in the
standard based on operation fraction that is defined to be a
fraction period of the day during which the building structure is
actually ventilated. Table 3 provides an example of the
effectiveness factor as a function of the operation fraction:
TABLE-US-00003 TABLE 3 ASHRAE 62.2 Effectiveness Operation Fraction
(F) Effectiveness (.epsilon.) F < 0.35 0.33 0.35 .ltoreq. F <
0.60 0.50 0.60 .ltoreq. F < 0.80 0.75 0.80 .ltoreq. F 1.00
[0033] As the result, the intermittent ventilation rate
(V.sub.intermittent) can be determined from the Operation Fraction
(F) and effectiveness (.epsilon.) factors as:
V intermittent = V base F * ( Eq . 3 ) ##EQU00003##
In a specific embodiment, the system 100 is operated at a
ventilation mode within a time period measured by the operation
fraction F that is associated with either an active period (during
daytime) for delivering a flow of fresh air carrying solar thermal
energy to provide space heating or a similar time period after the
active period for using the flow of fresh air for providing
night-flush cooling. For a typical residential home and low-rise
building structure, the active period of the system associated with
thermal energy generation and delivering is about 8+ hours daily,
for example, from 8:00 AM to about 4 PM. In an implementation of
the present invention, the time period dedicated for ventilation,
i.e. a ventilation period, can be specified as a daily fractional
period up to 24 hours, represented by the operation fraction factor
F. Additionally, comparing to steady full-day ventilation, a
shortened ventilation period of course yields different ventilation
effect. With an operation fraction factor F being set, ASHRAE
standard 62.2 requires the system operation to be run an optimized
intermittent ventilation with the `effectiveness` factor .epsilon.
mapped with the operation fraction factor F. In a specific
embodiment, the ventilation period is specified substantially in
association with the active period mentioned above. For example, an
8.5 hour runtime of the ventilation period is specified to run an
intermittent ventilation, that gives the operation fraction factor
F=0.354. Accordingly, the V.sub.intermittent for this home can be
calculated as:
V intermittent = 0.024 0.354 * 0.54 = 0.136 m 3 / s ( Eq . 4 )
##EQU00004##
The criteria for satisfying ASHRAE standard 62.2 will be a total
daily integrated airflow target V.sub.Target.sub.--.sub.day, that
would be equal to 4,162 m.sup.3 (0.136 m.sup.3/s.times.60
s/min.times.60 min/hr.times.8.5 hr) in above example. Of course,
the system at least can still use the base ventilation rate to
perform the ventilation continuously over 24 hours daily to
satisfying ASHRAE standard 62.2.
[0034] In another specific embodiment, the system 100 is configured
within a native operation mode to provide space heating/cooling to
the interior space of the building structure during a first time
period and is also enabled with a ventilation operation mode to
provide ventilation during a second time period. In one or more
embodiments, the ventilation mode utilizes an intermittent
ventilation operation logic that is designated to associate the
second time period with the first time period by coordinating the
ventilation operation with the native operation for providing space
heating/cooling by the system so that those operation hours are
accumulated for free home ventilation. Additionally, the
ventilation operation logic is implemented to avoid the highest
energy penalties for performing ventilation without adding thermal
loads for interior space heating/cooling. In conventional systems,
the high energy penalties may be caused by accruing the system for
ventilating with the coldest night air in winter (or generally in a
heating season or heating period) or the hottest daytime air in
summer (or generally in a cooling season or cooling period). The
ventilation operation logic according to the present invention is
added on top of general system control for space heating or
cooling. In another specific embodiment, the ventilation operation
logic is implemented such that in the heating season the
ventilation period (e.g., 8.5 hours or less) starts substantially
coincidentally with the beginning of the active period and in the
cooling season the ventilation period starts some time after the
active period has ended. Of course, the 8.5 hours ventilation
period setting is just an example. For different geological regions
or different climate conditions, the specified ventilation period
of a healthy home in association with the active period of the
system can be different, say, 10 hours, or 12 hours, or others.
[0035] It is also understood that the examples and embodiments
described herein are for illustrative purposes only and that
various modifications or changes in light thereof will be suggested
to persons skilled in the art and are to be included within the
spirit and purview of this application and scope of the appended
claims. Further details of a specific technique for monitoring and
verifying a solar-based home energy system can be found throughout
the present specification and more particularly below.
[0036] FIG. 2 is a simplified flow diagram illustrating a method
for providing ventilation to a healthy home in association with a
home energy system according to an embodiment of the present
invention. This diagram is merely an example, which should not
unduly limit the scope of the claims herein. One of ordinary skill
in the art would recognize other variations, modifications, and
alternatives. It is also understood that the examples and
embodiments described herein are for illustrative purposes only and
that various modifications or changes in light thereof will be
suggested to persons skilled in the art and are to be included
within the spirit and purview of this process and scope of the
appended claims.
[0037] As shown in FIG. 2, the present method can be briefly
outlined below. [0038] 1. Start; [0039] 2. Operate a home energy
system associated with a daily active period and draw fresh air;
[0040] 3. Set a daily ventilation period as a fraction period of a
day in association with the daily active period; [0041] 4.
Determine a target volume in compliance with a ventilation
standard; [0042] 5. Determine a flow rate for delivering the fresh
air during the daily ventilation period; [0043] 6. Perform
ventilation in the daily ventilation period to deliver the fresh
air using the flow rate; [0044] 7. Monitoring an accumulated total
ventilation volume until the accumulated total ventilation volume
is in a vicinity of the target volume; and [0045] 8. Stop.
[0046] These steps are merely examples and should not unduly limit
the scope of the claims herein. As shown, the above method provides
a way of performing ventilation using an intermittent system to
associate with a corresponding system active period within a
fraction period of a day according to an embodiment of the present
invention. In a preferred embodiment, the method uses a novel home
energy system that uses a controlled energy transfer module coupled
to a solar thermal module to perform an intermittent home
ventilation that coordinates with native space heating or space
cooling operation compliant with the adopted ASHRAE standard 62.2
or the likes for different geological regions or countries. One of
ordinary skill in the art would recognize many other variations,
modifications, and alternatives. For example, various steps
outlined above may be added, removed, modified, rearranged,
repeated, and/or overlapped, as contemplated within the scope of
the invention.
[0047] As shown in FIG. 2, the method 400 begins at start, step
405. The present method provides a home ventilation method based on
a home energy system including a controlled energy transfer module
coupled to a solar thermal module (see FIG. 1). Here, the method
begins at the home energy system implemented at a target
(residential) home (or building structure) and controlled by a
system controller configured to input a number of parameters
associated with local climate information and building setting
information including at least a floor area and bedroom counts. The
system controller adds a logic level dedicated for ventilation as
an additional control scheme within native system operations for
providing space heating or space cooling.
[0048] In step 410, the method 400 includes operating the home
energy system in association with an active period to utilize solar
thermal energy for providing space heating or space cooling. In an
embodiment, depending on a heating season or a cooling season, the
system is set and operated correspondingly in a heating mode or a
cooling mode. In either mode, the system is configured to operate
the solar thermal module at least within the daily active period
beginning from a specified start time till an end time to generate
thermal energy from solar energy source. In the heating mode, the
system controller is configured to determine a flow rate for a
blower of the energy transfer module to draw a flow of fresh air
from ambient and control a damper to deliver the flow into the
building structure. In the cooling mode, the system controller can
close the damper to shut out the flow into the interior region of
the home, instead, to use another damper to direct the heated flow
to exhaust port during the active period, but open the damper to
send the flow in for providing cooling effect during another time
period (usually in the night) after the active period. The system
controller monitors energy production by the solar thermal module
during the active period operation and controls the processing of
the collected flow inside the energy transfer module for utilizing
the solar thermal energy at least partially. As an example in a
heating season, the system can trigger a space heating operation
within the active period to direct deliver heated flow of the fresh
air from the energy transfer module into the home whenever the
actual indoor temperature condition indicates a space heating is
required under criteria based on corresponding home comfort
settings. The daily active period is typically about 8.5 hours
depending on sun rise and set time. For example, the active period
is specified to start from 8:00 AM to 4:30 PM. Depending on
seasoning and geological difference, the daily active period may be
longer, such as 10 hours or more. Of course, there can be other
variations, modifications, and alternatives.
[0049] The method 400 further includes a step 415 of setting a
daily ventilation period for the home. The ventilation control
logic behind the method 400 is intended to perform an intermittent
ventilation in a time period that is a fractional period of a full
day to take advantage of native system operations for space heating
or cooling for avoiding high energy penalties while still
satisfying the ASHRAE standard 62.2. The daily ventilation period
can be specified as a fractional time period of 24 hours. For
example, a shortened ventilation period is 8 hours, or 10 hours, up
to 24 hours. The ratio of the specified ventilation period over the
total 24 hours per day gives the operation fraction factor F. For
example, a shortened ventilation period is set to be 8.5 hours,
then F=0.354. In an embodiment, the daily ventilation period is
associated with the daily active period to coordinate the
ventilation with the native system operations for providing space
heating or space cooling. In particular, when the system is set in
the heating mode and the active period is associated with a period
of time when the system is generating solar thermal energy and
drawing a flow of fresh air carrying the thermal energy. The heated
fresh air is capable of providing space heating to the interior
region of the home. Therefore, on the one hand if the ventilation
period is set substantially coincident with the daily active
period, the fresh air as delivered for ventilation also provides
space heating for the home during a heating season (for example,
winter time), saving energy required for heating. On the other
hand, the ventilation is shut down during the off time for
generating solar energy, then the fresh air from cold ambient
region is not delivered into the home, so as to avoid increasing
the extra energy cost for heating the cold air. When the system is
set to the cooling mode, it means that the heated air should be
avoided to be delivered into the home. Therefore, the daily
ventilation period is set to start from a time period after the
active period when no solar thermal energy is generated and more
preferably the solar panel is cooled and can serve as a radiation
cooler for the fresh air passed by. In an example, the ventilation
period is set to start in evening time, e.g. 90 minutes after the
active period ends. Then the fresh air as delivered for ventilation
is also providing flush cooling for the interior region of the
home, saving energy usage for nominal air conditioning. More
importantly, the ventilation period as set in step 415 avoids
delivering heated air into the home during a period with peak
cooling load, substantially reducing the energy penalty for space
cooling in order to satisfy the ventilation requirement.
[0050] The method 400 additionally includes a step 420 to determine
a daily ventilation target volume for ventilation within the daily
ventilation period in compliance with an adopted ventilation
standard. Based on the adopted ventilation standard, daily home
ventilation corresponds to a process for delivering a flow of fresh
air continuously with a constant flow rate for a full day. Using
the ASHRAE standard 62.2 as an example, a base ventilation rate can
be calculated based on a number of parameters associated with
information related to home setting including at least a floor area
and bedroom counts (see Table 1) stored in the system controller.
By setting a daily ventilation period that is a shortened time
period (vs. a full day), daily home ventilation is an intermittent
ventilation for delivering the flow of fresh air using an
intermittent rate. The ventilation control logic implemented in
present invention is based on an integrated airflow over the full
day period that is `equivalent` to home ventilation performing at
the intermittent rate within the shortened time period
corresponding to a fraction factor F. Here the equivalence leads to
a consideration of an effectiveness factor .epsilon. (see Table 3)
which depends on the fraction factor F. As seen in the descriptions
earlier and particularly in Eq. 3, the intermittent rate can be
provided from the base rate, the fractional factor F and the
effectiveness factor .epsilon.. In the example mentioned earlier, a
8.5 hours is set as daily ventilation period, the intermittent rate
is determined to be 0.136 m.sup.3/s for a home with 200 m.sup.2
(2,000 ft.sup.2) floor area and 3 bedrooms under the ASHRAE
standard 62.2. Then a total flow volume can be obtained by
multiplying the flow rate with the ventilation time, that is, 0.136
m.sup.3/s.times.60 s/min.times.60 min/hr.times.8.5 hr=4,162
m.sup.3. In an embodiment, the daily ventilation target volume is
determined by the total volume to deliver the air in the specified
daily ventilation period using the intermittent rate. Of course,
there can be other variations, modifications, and alternatives.
[0051] In step 425, the method 400 determines a flow rate for
delivering the flow of the fresh air into an interior region of the
building structure for ventilation during the daily ventilation
period. In order to be compliant with the adopted ventilation
standard, the flow rate is set to be equal to or greater than the
intermittent ventilation rate required by the system to perform
ventilation effectively during the specified daily ventilation
period that is shorter than a full day. If the system is in a
native space heating mode that operates a solar thermal module to
generate solar thermal energy and draw a flow of fresh air, the
system is configured to drive a blower with a flow rate to deliver
the flow of fresh air carrying the solar thermal energy into the
interior space of the home. The method 400 thus just uses the step
425 to set the same flow rate for performing ventilation. As a
result, the ventilation takes advantage of a native system
operation for space heating and the actual ventilation time may be
even shorter than the specified daily ventilation time to reach the
daily ventilation target volume because the flow rate is usually
much higher than the intermittent rate. Alternatively, if the
system is not operated in native heating mode, the method 400 uses
step 425 to set the flow rate at the intermittent rate for
performing the ventilation during the daily ventilation period. Of
course, there can be other variations, modifications, and
alternatives. In an example, the system may turn off its native
operation for space heating or space cooling and a continuous
ventilation mode may be executed with a constant flow rate that is
equal to the base rate according to the ventilation standard for
the specific home.
[0052] Through the system controller, the system ventilation logic
is further implemented, step 430, to perform ventilation in the
daily ventilation period to deliver the fresh air using the flow
rate set in step 425. As mentioned earlier, the daily ventilation
period is set to be associated with the daily active period in step
415. During a heating season for the system, the daily ventilation
period is substantially coincident with the active period
(typically in the day time for utilizing solar energy). In this
way, the flow of the fresh air drawn by the solar thermal module
and delivered from the energy transfer module carries thermal
energy for providing space heating and home ventilation at the same
time. In an example above, the start time for setting the blower of
the energy transfer module at the intermittent rate is
substantially the same as the start time of the active period for
producing solar thermal energy. As the ventilation continues, the
energy transfer module operates the blower with a flow rate at
least no smaller than the intermittent rate. When the system is
operated in a native space heating mode, the natural flow rate to
deliver the flow of the (heated) fresh air can become much higher
than the intermittent rate. Furthermore, the ventilation period may
be cut off the same time or even earlier than the end time of the
active period if the target volume of ventilation is reached so
that the system avoids adding cooling load to the home energy
system after the end time of the active period for performing
ventilation. During a cooling season for the system the daily
ventilation period is within a predetermined time period after an
end of the active period. When the system is operated in a native
space cooling mode, it is more energy efficient overall to avoid
delivering the flow of the fresh air that may be heated by the
solar thermal module during the active period. Instead, the
ventilation period is set to begin at some time, e.g. 90 minutes,
after the end of the active period (usually in the evening or
later) to supply the flow of the fresh air that is further cooled
by radiation from the solar thermal module.
[0053] The method 400 includes, step 435, monitoring an accumulated
ventilation flow volume to determine if the accumulated flow volume
up to a current time meets the daily ventilation target volume
determined in step 420. The accumulated ventilation airflow volume
can be calculated using an airflow volume performance data
collected for every 15-minute runtime stored in system controller.
In an example, the 15-minute runtime airflow volume performance
data stored in the system controller is compared with a flow volume
with the intermittent rate during the same 15 minutes. Only the
smaller value among them is credited in compliance with the ASHRAE
standard 62.2 and is used for summing up over the ventilation
runtime to obtain the accumulated ventilation volume up to a
current time. In another embodiment, the ventilation control logic
under the method 400 sets the daily target volume as the criteria
to cut off the ventilation. Although the shortened ventilation
period has been coordinated with the active period, the actual
accumulated ventilation volume may reach the target volume before
the end of the active period due to operation variation, ambient
climate change, indoor condition change, and system mode setting
change. Of course, there can be other variations, alternatives, and
modifications.
[0054] The above sequence of processes provides a method for
performing an intermittent ventilation under a healthy home system
in compliance with the ASHRAE standard 62.2 according to an
embodiment of the present invention. As shown, the method uses a
combination of steps including supplying an ambient fresh airflow
carrying thermal energy (for space heating and cooling) to provide
home ventilation in coordination with the native space heating or
space cooling operation. Other alternatives can also be provided
where steps are added, one or more steps are removed, or one or
more steps are provided in a different sequence without departing
from the scope of the claims herein. Examples about implementing
the present method can be found throughout the present
specification and more particularly below.
[0055] FIG. 3 is an exemplary diagram illustrating a daily
ventilation rate plot for a home according to an embodiment of the
present invention. This diagram is merely an example, which should
not unduly limit the scope of the claims herein. One of ordinary
skill in the art would recognize other variations, modifications,
and alternatives. As shown, an example of what a single day
ventilation cycle for a home of about 2000 ft.sup.2 in a heating
season would look like. For a 24 hours time period, the system is
operated with a heating mode in association with an active period
starting at 8:00 AM and the energy transfer module begins
ventilating the indoor zone at V.sub.intermittent rate following a
ventilation plan for satisfying the ASHRAE standard 62.2. At 10:00
AM space heating operation of the system turns on and begins
delivering fresh air with a much higher flow rate to the home based
on a native space heating logic. However, although during the
native space heating mode ventilating occurs at a much higher rate,
the logic in the ASHRAE standard 62.2 means that only the
intermittent rate value (For example, see Eq. 4) is credited. This
process continues to last till the end of the specified active
period for space heating, at .about.4:30 PM the ventilation cycle
is cut off after achieving our 8.5 hours of runtime at
V.sub.intermittent rate. The specified time period for intermittent
ventilation is substantially coincident with the active period and
the ventilation rate is cut off almost at the same time as the
active period ends.
[0056] The active period at least partially is specified based on a
preferred period for solar module to work at its best efficiency to
generate (electrical and thermal) energy out of solar energy
source. The space heating operation of the system that utilizes the
solar thermal energy would be preferably carried out during the
active period. By associating the daily ventilation period with the
active period for space heating is able to supply fresh air into
the home substantially free in causing extra energy penalty. After
the active period, other forms of heating may be triggered for
meeting the home comfort requirement while no need to deliver cold
air into the home for any ventilation purpose.
[0057] FIG. 4 is an exemplary diagram illustrating a daily
ventilation volume plot for a home according to an embodiment of
the present invention. This diagram is merely an example, which
should not unduly limit the scope of the claims herein. One of
ordinary skill in the art would recognize other variations,
modifications, and alternatives. Although the ASHRAE standard 62.2
is designed to run ventilation at a fixed flow rate and over a full
day time period, the ventilation logic provided according to
embodiments of the present invention is based on an integrated
airflow volume as a criteria running at the V.sub.intermittent over
the specified ventilation period, say 8.5 hours, that is
`equivalent` to the full day fixed rate ventilation. In the case
above, the integrated airflow target volume
V.sub.Target.sub.--.sub.day would be 4,162 m.sup.3 (0.136
m.sup.3/s.times.60 s/min.times.60 min/hr.times.8.5 hr). As shown,
the target airflow volume 4,162 m.sup.3 is reached at 16:00 and
ventilation is cut off somewhat sooner than the specified 8.5 hr
shortened ventilation period. The rationale behind this is that
there might be some airflow variance in the system due to ambient
effects (e.g. wind) or native system operation (e.g. the energy
transfer module goes into a sampling mode for a few minutes). The
internal system logic is therefore running with an
integrator/accumulator that would track to the daily target airflow
volume, 4,162 m.sup.3. Of course, there can be other variations,
alternatives, and modifications.
[0058] It is also understood that the examples and embodiments
described herein are for illustrative purposes only and that
various modifications or changes in light thereof will be suggested
to persons skilled in the art and are to be included within the
spirit and purview of this application and scope of the appended
claims. Further details of a specific control technique and logic
sequence for monitoring the ambient climate and indoor condition,
monitoring the solar thermal module, and operating an energy
transfer module in a intermittent ventilation coordinated with
native space heating/cooling, can be found throughout the present
specification and more particularly below.
[0059] FIGS. 5A-5D are simplified flow diagrams illustrating a
method for providing daily home ventilation for a healthy home in
association with a home energy system according to a specific
embodiment of the present invention. These diagrams are merely
examples, which should not unduly limit the scope of the claims
herein. One of ordinary skill in the art would recognize other
variations, modifications, and alternatives. It is also understood
that the examples and embodiments described herein are for
illustrative purposes only and that various modifications or
changes in light thereof will be suggested to persons skilled in
the art and are to be included within the spirit and purview of
this process and scope of the appended claims.
[0060] As shown in FIG. 5A, part of the present method 500 can be
briefly outline below. [0061] 1. Start; [0062] 2. Operate a home
energy system (The `system`) for providing fresh air for
ventilation; [0063] 3. Deliver a flow of the fresh air carrying
solar thermal energy into an interior region of the building
structure; [0064] 4. Calculate a 15-min. integrated volume over
daily runtime; [0065] 5. Determine daily ventilation target volume
compliant with ASHRAE standard 62.2 based on an intermittent rate
within a daily ventilation period; [0066] 6. Determine if a system
is set in a heating mode or cooling mode; [0067] 7. In the heating
mode, perform process A, in the cooling mode, perform process B,
and when the system is off, determine if T_ambient<a
pre-specified temperature value; [0068] 8. T_ambient<the
pre-specified temperature value true, perform process A,
T_ambient<the pre-specified temperature value not true, perform
process B;
[0069] These steps are merely examples and should not unduly limit
the scope of the claims herein. As shown, the method provides a way
for ventilating the home with efficient energy usage and
conservation of energy resources by a coordination between
ventilation process and native space heating/cooling operation
under a home energy system utilizing solar thermal energy according
to an embodiment of the present invention. One of ordinary skill in
the art would recognize many other variations, modifications, and
alternatives. For example, various steps outlined above may be
added, removed, modified, rearranged, repeated, and/or overlapped,
as contemplated within the scope of the invention.
[0070] As shown in FIG. 5A, the method 500 begins at start, step
505. The present invention provides a method for adding a logic
level dedicated for ventilation control over native space heating
and space cooling operations under a home energy system (see FIG.
1) installed for a specific residential home or low-rise building
structure. The sequential steps outline the ventilation control
logic implemented by a system controller. The system controller is
able to set a proper ventilation rate for a blower to drive an
ambient airflow through an energy transfer module within the home
energy system capable of utilizing solar thermal energy to provide
space heating and space cooling for the building structure at least
in association with an active period for solar energy production
per day. An input data file named config.dat includes parameters
like floor area and bedroom counts and is stored into the
controller memory. Here, the method 500 begins with operating the
home energy system (i.e., the system) for providing a flow of fresh
air into an interior region of a building structure for home
ventilation, step 510.
[0071] The method 500 further executes a step 515 for delivering a
flow of the fresh air collected by the solar thermal module from an
ambient region. The flow of fresh air carries the solar thermal
energy generated by the solar thermal module along its way through
the energy transfer module into an interior region of the building
structure to provide ventilation of the interior region of the
building structure. The system is configured to use the energy
transfer module to measure the flow volume whenever the blower (see
FIG. 1) is in operation and a damper in an outlet (see FIG. 1) is
open for delivering the flow of the fresh air into an interior
space region of the building structure. For every 15 minutes
runtime, the flow volume delivered to the building structure can be
measured based on sensor data collected by one or more sensors in
upstream region and downstream region communicating with the blower
in the energy transfer module. Continuously over operation time for
a full day, the 15-minute integrated flow volume is saved in a
float data file stored into the system controller memory, step 520.
One skilled in the art would recognize many variations,
modifications, and alternatives.
[0072] In another embodiment, the method 500 further includes a
step 525 for activating the system controller to determine a target
volume within a daily ventilation period for a compliance of an
adopted ventilation standard, e.g., ASHRAE standard 62.2. The
present control logic is designed to implement the intermittent
ventilation by operating the system in the specified daily
ventilation period ranging from a fractional time period of the
full day up to 24 hours while ensuring the total ventilation air
flow to be substantially equivalent to that satisfying the
requirement of the adopted ventilation standard. Accordingly, the
target volume for the intermittent ventilation can be determined
from an intermittent rate for performing the ventilation during the
daily ventilation period. By specifying the daily ventilation
period, a fractional factor F is obtained and correspondingly an
effectiveness factor .epsilon. can be determined (for compensating
a shorter ventilation time per day with an enhanced ventilation
power). In a specific embodiment, the daily ventilation period is
set to be associated with an active period when solar energy is
generated by the system or associated with a time period after the
active period when radiation cooling is provided so that the
ventilation process can be coordinated with system native
operations for space heating/cooling. In particular, the active
period is associated with solar thermal energy production by the
solar thermal module, beginning at a start time and ending at an
end time. In another specific embodiment, the intermittent rate
corresponding to a specified daily ventilation period can be
provided from a base rate used for continuous ventilation for a
full day based on the ventilation standard. For a specific
residential home or low-rise building structure, a number of home
parameters include floor area, number of floors, number of
bedrooms, etc. can be provided and pre-inputted into the system
controller. For example, this is available in Echo.TM. system
provided by EchoFirst, Inc. (PVT Solar, Inc.). Using the ASHRAE
standard 62.2 as an example, the base rate can be calculated from
the number of home parameters using Eq. 1. Further, the
intermittent rate to perform ventilation within the daily
ventilation period can be obtained from the equivalence
relationship between the intermittent ventilation and the
continuous ventilation performed with the constant base rate for a
full day according to the ASHRAE standard 62.2. Therefore, a daily
ventilation target volume can be determined by directly multiplying
the intermittent rate with the total time in the specified
ventilation period. Of course, there can by many variations,
modifications, and alternatives. For example, the number of home
parameters may be not available for a particular system, then a
base ventilation rate will be just set to 0.030 m.sup.3/s,
according to the ASHRAE standard 62.2. In an alternative
embodiment, the daily ventilation period may not be a single
continuous time period and can be a combination of several time
periods with different start and end time.
[0073] The method 500 adds a logic level over native operation mode
by enabling a ventilation mode for the system. In an embodiment,
the control logic raises a flag as to whether or not the controller
should enable the ASHRAE 62.2 logic. As see in Table 1, a binary
parameter IAQ_Ventillation_enablence saved in the config.dat file
represents the flag for ventilation control logic. For example, if
IAQ_Ventillation_enablence parameter is assigned value 1, turn on
the ventilation logic; if IAQ_Ventillation_enablence parameter is
assigned value 0, disable the ventilation logic.
[0074] The method 500 also includes a step 530 for determining if
the system is set in a heating mode or in a cooling mode. In one or
more embodiments, the system setting in either a heating or cooling
mode is associated with local climate condition and interior
comfort requirement. This step is associated with an enablement of
a native system control logic for providing space heating or space
cooling and can be independent from the enablement status of the
ventilation logic. In a specific embodiment, the method 500
performs the step from the start time of the active period for the
day using a communication between the controller and a thermostat
installed inside the home (see FIG. 1). If the thermostat has its
mode of operation set (automatically or manually) to "Heat", the
system then determines that it is in the heating mode. If the
thermostat has its mode of operation set to "Cool", the system then
determines that it is in the cooling mode. In a scenario that the
thermostat is not in either discrete mode by setting to "Off" or
not even installed, the system can trigger another step 535 of
using information about ambient temperature depending on a heating
season or a cooling season. If the ambient temperature is lower
than a pre-specified temperature value, for example 15 C..degree.,
the system determines that it should be set in a heating mode,
otherwise it should be set in a cooling mode. Of course, there are
many variations, alternatives, and modifications.
[0075] The above sequence of processes provides a method for adding
a level of control logic to perform ventilation on top of current
native system operation, either operated for providing space
heating (in a native space heating mode) or space cooling (in a
native space cooling mode) according to one or more embodiments of
the present invention. Other alternatives can also be provided
where steps are added, one or more steps are removed, or one or
more steps are provided in a different sequence without departing
from the scope of the claims herein. Further details of the present
method can be found throughout the present specification and more
particularly below.
[0076] As shown in FIG. 5B, the present method 500 is further
executing a ventilation logic when the system is set in a heating
mode. The ventilation logic can be briefly outlined below. [0077]
9. Begin the daily ventilation period from the start time with a
flow rate no smaller than the intermittent rate; [0078] 10.
Calculate an accumulated ventilation volume from the start time to
a current time; [0079] 11. Determine if the accumulated ventilation
volume is smaller than daily ventilation target volume; [0080] 12.
Perform ventilation with at least the intermittent rate if the
accumulated ventilation volume is determined to be smaller than
daily ventilation target volume; and [0081] 13. Cut off ventilation
if the accumulated ventilation volume is determined to be no
smaller than daily ventilation target volume; [0082] 14. Stop.
[0083] These steps are merely examples and should not unduly limit
the scope of the claims herein. As shown, the above method provides
a level of ventilation control logic to deliver a flow of the fresh
air from ambient via the energy transfer module in a daily
ventilation period which is associated with an active period within
the day for the solar thermal module to generate solar thermal
energy carried by the flow of the fresh air according to an
embodiment of the present invention. In a preferred embodiment, the
method first sets the daily ventilation period to start
substantially coincidentally with the start time of the active
period, then monitoring a progress of the ventilation in terms of
an accumulated flow volume to compare with the daily ventilation
target volume. The active period, in an example, can start from
8:00 AM and end at 4:30 PM each day. The daily ventilation period
can be specified as 8.5 hours, substantially having a same start
time at 8:00 AM. One of ordinary skill in the art would recognize
many other variations, modifications, and alternatives. For
example, various steps outlined above may be added, removed,
modified, rearranged, repeated, and/or overlapped, as contemplated
within the scope of the invention.
[0084] Once the system is determined to be set in the heating mode
and is enabled with the ventilation logic, at the start time of
ventilation the system sets the flow rate for the blower of the
energy transfer module (See FIG. 1) at a rate no smaller than the
intermittent rate V.sub.intermittent and open the damper in the
outlet (FIG. 1) for delivering the flow of the fresh air carrying
certain amount of thermal energy into the interior region of the
building structure, the step 541. At any current time after
starting the ventilation, the ventilation control logic implemented
by the system controller keeps monitoring the progress of the
ventilation and calculating a daily integrated ventilation flow
volume from the start time of the ventilation up to the current
time. In a specific embodiment, the energy transfer module is
configured to record a 15-minute performance data
V.sub.ventillation of integrated airflow volume and calculate a
projected airflow volume using the intermittent ventilation rate
within the same 15-minute time span. The control logic provides, in
step 551, an accumulated ventilation volume V.sub.day from the
start time of the active period as:
V.sub.day=.SIGMA.(Min(V.sub.ventillation,V.sub.intermittent.times.60.tim-
es.15)) (Eq. 5)
and sums up all the values for every 15-minute time span over all
ventilation runtime from the start time up to the current time.
[0085] The ventilation logic further includes a step 561 to
determine if the accumulated ventilation volume is smaller than the
daily ventilation target volume (see step 520). If a returned logic
value of step 561 is true, it means that additional ventilation is
necessary for satisfying the ventilation standard, ASHRAE standard
62.2. The method 500 now in fact triggers a loop of control
operations, first executing a step 574 for continuing ventilation
by setting the blower of the energy transfer module to drive the
fresh air at a flow rate that is equal to or greater than the
intermittent rate, then moving back to step 551 to obtain an
updated value of the accumulated ventilation volume V.sub.day,
followed by performing the step 561 again. Only if the returned
logic value of step 561 is False, then does the method trigger the
next step 571 to cut off the ventilation. The method 500 for
performing the intermittent ventilation process under the home
energy system can be stopped at the step 599. Further detailed
description about executing the step 574 on how to perform the
ventilation throughout the specified daily ventilation period will
be found below.
[0086] As shown in FIG. 5C, the present method 500 alternatively is
executing a ventilation logic when the system is set in a cooling
mode. The ventilation logic can be briefly outlined below. [0087]
9. Keep the system in the cooling mode until a predetermined time
after the end time of the active period to begin the daily
ventilation period for delivering fresh air at a rate no smaller
than the intermittent ventilation rate; [0088] 10. Calculate an
accumulated ventilation volume to a current time; [0089] 11.
Determine if the accumulated ventilation volume is smaller than
daily ventilation target volume; [0090] 12. Perform ventilation
with at least the intermittent ventilation rate if the accumulated
ventilation volume is determined to be smaller than daily
ventilation target volume; and [0091] 13. Cut off ventilation if
the accumulated ventilation volume is determined to be no smaller
than daily ventilation target volume; [0092] 14. Stop.
[0093] These steps are merely examples and should not unduly limit
the scope of the claims herein. As shown, the above method provides
a level of ventilation control logic to deliver a flow of the fresh
air from ambient via the energy transfer module in a daily
ventilation period which is associated with a time period after the
end time of the active period within the day by the system set in a
cooling mode according to an embodiment of the present invention.
In a preferred embodiment, the method first sets the daily
ventilation period to start at a predetermined time after the end
time the active period, then monitoring a progress of the
ventilation in terms of an accumulated flow volume to compare with
the daily ventilation target volume. The active period, as
mentioned in an earlier example, can start from 8:00 AM and end at
4:30 PM each day. The start time for the daily ventilation period
may be specified at 90 minutes after the end time of the active
period. In the mentioned example, the daily ventilation period can
be specified to be 8.5 hours, starting substantially at 6:00 PM or
later and ending at 2:30 AM next day. One of ordinary skill in the
art would recognize many other variations, modifications, and
alternatives. For example, various steps outlined above may be
added, removed, modified, rearranged, repeated, and/or overlapped,
as contemplated within the scope of the invention.
[0094] Once the system is determined to be set in the cooling mode
and is enabled with the ventilation logic, the system controller
keeps the system in the cooling mode and wait until the active
period ends to begin the ventilation operation after that. Usually,
the cooling mode is set for corresponding with a hot outdoor
climate condition, for example the summer time. Therefore, the
ventilation control logic is designed to delay the start of
ventilation until a certain time, e.g. 90 minutes or later, after
the end time of the active period to deliver a flow of the fresh
air with at least the intermittent rate, step 542. This ventilation
control logic avoids letting the system to deliver hot ambient air
into the home to cause substantial increases of the cooling load to
the system. Eventually when evening comes and ambient air
temperature drops, the daily ventilation period of the system can
start as the system controller sets the blower of the energy
transfer module at a rate no smaller than the intermittent rate
V.sub.intermittent and open the damper in the outlet (see FIG. 1)
for delivering the flow of the fresh air at a reduced temperature.
In an specific embodiment, a panel structure of the solar thermal
module serves as a radiation cooling tool that is able to cool the
fresh air collected in the air plenum structure (see FIG. 1). The
cooled fresh air is delivered into the interior region of the
building structure for providing ventilation and space cooling with
much reduced cooling loads (or at least without causing increase in
cooling loads).
[0095] At any current time after starting the daily ventilation at
the step 542, the ventilation control logic implemented by the
system controller is monitoring the progress of the ventilation and
calculating a daily integrated ventilation volume from the start
time of the ventilation up to the current time. In a specific
embodiment, the energy transfer module is configured to record a
15-minute performance data V.sub.ventillation of integrated airflow
volume and calculate a projected airflow volume using the
intermittent ventilation rate within the 15-minute time span. The
control logic deduces, in step 552, an accumulated ventilation
volume V.sub.day from the start of the daily ventilation period
as:
V.sub.day=.SIGMA.(Min(V.sub.ventillation,V.sub.intermittent.times.60.tim-
es.15)) (Eq. 6)
and sums up all the values for every 15-minute time span over all
runtime from the start time up to the current time.
[0096] The ventilation logic further includes a step 562 to
determine if the accumulated ventilation volume is smaller than the
daily ventilation target volume (see step 520). If a returned logic
value of step 562 is True, it means that additional ventilation is
necessary for satisfying the ASHRAE standard 62.2. The method 500
now in fact triggers a loop of control steps, first executing a
step 575 for continuing ventilation by setting the blower of the
energy transfer module to drive the fresh air at a flow rate that
is equal to or higher than the intermittent rate, then moving back
to step 552 to obtain an updated value of the accumulated
ventilation volume V.sub.day, followed by performing the step 562
again. Only if the returned logic value of step 562 is False, then
does the method trigger the next step 572 to cut off the
ventilation. The method 500 for performing the intermittent
ventilation process under the home energy system can be stopped at
the step 599. Further detailed description about executing the step
575 on how to perform the ventilation throughout the specified
daily ventilation period will be found below.
[0097] As shown in FIG. 5D, the present method 500 is further
executing a ventilation logic during a process for continuing
ventilation with at least the intermittent ventilation rate.
Depending on the system identified to be in a heating (or cooling)
mode at a start time of the daily ventilation period, the process
574 (575) includes an additional process or a loop of processes for
performing ventilation. In a specific embodiment, the system
controller triggers a step 591 (592) to determine if the system is
actually operated at a native space heating mode or a native space
cooling mode. If the logic value of step 591 (592) is True, the
system controller automatically sets the blower of the energy
transfer module to drive the flow of the fresh air at a first or
second flow rate pre-programmed for performing the native space
heating operation or space cooling operation. Either the first or
the second flow rate can be much higher than the intermittent rate
(step 520). In other words, the system operation according to
embodiments of the present invention sets a higher priority for
operating the native space heating/cooling mode to meeting home
comfort thermal loads, ventilation logic being set at a lower
priority. Then the step 574 (575) is accomplished and moved back to
step 561 (562) in the control loop.
[0098] If the logic value of step 591 (592) is False, i.e., the
system is not actively providing space heating or space cooling.
Then the system controller enters another logic step 595 (596) to
determine if a current indoor zone temperature T.sub.zone is either
below a pre-set upper bound value T.sub.zone.sub.--.sub.max of a
temperature comfort band setting even though the system was set in
the heating mode, or above a pre-set lower bound value
T.sub.zone.sub.--.sub.min of the temperature comfort band setting
even though the system was set in the cooling mode. If the logic
step 595 (596) yields a True value, the system controller will
continue, at step 597, to set the blower at the intermittent rate
for performing ventilation. If the logic step 595 (596) yields a
False value, the system controller moves to execute step 581 (582)
to cut off the ventilation. Then the step 574 (575) is accomplished
and moved back to step 561 (562) in the control loop.
[0099] The above sequence of processes provides a method for
enabling an ASHRAE ventilation mode of a home energy system to
deliver fresh ambient air into a residential home or a low-rise
building structure for ventilation according to an embodiment of
the present invention. As shown, the method uses a combination of
steps including continuously metering air flow volume delivered to
the home & writing to a 15-minute float data file, determining
a daily ventilation target volume compliant with the ASHRAE
standard 62.2, determining if the local climate is in heating
season or cooling season, and operating a ASHRAE ventilation mode
if enabled. In a specific embodiment, the ventilation control logic
is configured to perform ventilation using the base ventilation
rate associated with the ASHRAE standard 62.2 for 1 hour if it is
determined that there has not been ventilation to the home in the
past 11 hours based on the daily float data table. In another
specific embodiment, the ventilation control logic is configured to
operate the system to perform ventilation in a full day 24 hours
with the base ventilation rate determined from the climate and
home-specific parameters including home area and bedroom counts for
satisfying the ASHRAE standard 62.2. In yet another specific
embodiment, the ventilation control logic is configured to be
applied for being compliant with other ventilation standards
adopted by different countries, international organizations, and
regional governments. Other alternatives can also be provided where
steps are added, one or more steps are removed, or one or more
steps are provided in a different sequence without departing from
the scope of the claims herein.
* * * * *