U.S. patent application number 11/667127 was filed with the patent office on 2008-05-29 for reduction of power consumption.
This patent application is currently assigned to R.L.I. BYGGDATA AKTIEBOLAG. Invention is credited to Lars-Olof Andersson, Alexander Engstrom.
Application Number | 20080121367 11/667127 |
Document ID | / |
Family ID | 33488181 |
Filed Date | 2008-05-29 |
United States Patent
Application |
20080121367 |
Kind Code |
A1 |
Andersson; Lars-Olof ; et
al. |
May 29, 2008 |
Reduction Of Power Consumption
Abstract
The invention relates to a method for temporary reduction of
electrical power consumption for cooling of buildings where the
cooling energy is stored in slab or wall, comprising the step of
storing cooling energy in at least some part of the slab (4) or the
wall (1,2,3) by means of that, during at least one period of time
when the electrical transmission network system can supply the
necessary electrical cooling machine power, supply cooling machine
cooled supply air to channels (5) arranged in the slab (4) or the
wall (1,2,3), and the step that, during at least one period of time
when the electrical transmission network system is highly loaded,
reduce the electrical power consumption of the cooling machine (28)
and at the same time convey supply air through the building through
the mentioned channels (5), which supply air when entering the
channel (5) is warmer than the surrounding slab surface or wall
surface adjacent to supply air terminal devices (6), hereby using
the earlier in the slab (4) or wall (1,2,3) stored cooling energy
to cool the supply air.
Inventors: |
Andersson; Lars-Olof;
(Saltsjobaden, SE) ; Engstrom; Alexander;
(Saltsjobaden, SE) |
Correspondence
Address: |
DICKSTEIN SHAPIRO LLP
1825 EYE STREET NW
Washington
DC
20006-5403
US
|
Assignee: |
R.L.I. BYGGDATA AKTIEBOLAG
Saltsjobaden
SE
|
Family ID: |
33488181 |
Appl. No.: |
11/667127 |
Filed: |
November 7, 2005 |
PCT Filed: |
November 7, 2005 |
PCT NO: |
PCT/SE2005/001670 |
371 Date: |
May 7, 2007 |
Current U.S.
Class: |
165/53 |
Current CPC
Class: |
Y02E 60/147 20130101;
F24F 2005/0025 20130101; F24F 5/0017 20130101; F24F 13/0227
20130101; Y02E 60/14 20130101; F24F 2005/0032 20130101 |
Class at
Publication: |
165/53 |
International
Class: |
F24D 19/02 20060101
F24D019/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 8, 2004 |
SE |
0402711-6 |
Claims
1. Method for temporary reduction of electrical power consumption
for cooling of buildings where the cooling energy is stored in slab
or wall, comprising the step of: storing cooling energy in at least
some part of the slab or the wall by means of that, during at least
one period of time when the electrical transmission network system
can supply the necessary electrical cooling machine power, supply
cooling machine cooled supply air to channels arranged in the slab
or the wall, and further characterized by the step, that: during at
least one period of time when the electrical transmission network
system is highly loaded, reduce the electrical power consumption of
the cooling machine and at the same time convey supply air through
the building through the mentioned channels, which supply air when
entering the channel is warmer than the surrounding slab surface or
wall surface adjacent to supply air terminal devices, hereby using
the earlier in the slab or wall stored cooling energy to cool the
supply air.
2. Method according to claim 1, characterized by the step, that the
slab or wall is made of concrete.
3. Method according to claim 1, characterized by the step, to store
cooling energy in slabs of prefabricated hollow core slabs or
cast-in-situ concrete slabs with embedded channels.
4. Method according to claim 1, characterized by the step, to store
cooling energy in at least some part of the slab or the wall by,
during at least one period of time when addition of outdoor air is
not required, re-circulating cooling machine cooled room air in
channels arranged in the slab or the wall.
5. Method according to claim 1, characterized by the step, to
reduce the electrical power consumption for the cooling machine by
decreasing the supply air flow during at least a period of time
when the when the electrical transmission network system is highly
loaded.
6. Method according to claim 1, characterized by the step, that
with the assistance of an ejector, or a fan, further cool the room
air by that parts of the room air is passed through the slab or the
wall.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a method for temporary
reduction of power consumption for cooling of buildings.
BACKGROUND
[0002] During recent years an increased use of electricity has
resulted in that the production capacity and the electrical
transmission network systems have been over-used. This concerns
above all over-developed city centres with large shares of offices
as these buildings must be provided with necessary power for
lighting, computers with peripheral equipment and above all for
cooling equipment. The last mentioned is of course even more of
interest in hotter climates, for example near the equator.
[0003] The reason for over-use of electrical transmission network
systems is the lack of accessible power for cooling machines when
the offices open in the morning and all of the cooling equipment is
turned on almost simultaneously. During the rest of the day the
power is then further increased when the outdoor temperature
increases and the supply air for ventilation of the offices needs
more cooling. To be able to manage the supply during the most
critical period, very radical measures may sometimes be demanded.
The department of energy in a country may for example demand that
the power consumption of a building is reduced by 50% during 5
hours. To increase the cost for the power which is consumed during
a certain time of the day may also be a way to decrease the power
consumption.
[0004] A method which has been developed to manage the lack of
electrical power for the cooling machines is district cooling,
where one in cities near oceans or big lakes can obtain direct
cooling, provided that the water in the ocean or the lake is cold
enough, by burying in the streets large insulated conduits
providing the buildings with necessary cooling water power through
heat exchangers, hereby decreasing the power consumed by the
cooling machines. Air treatment and cooling plants that are used in
this cooling method are mainly in operation only during the office
hours. In which way the marine local environment will be affected
in the long term is still unclear. The drawbacks with district
cooling are several. The investment cost is high and the buildings
must be situated close enough together and near a water system in
order for it to be practically and economically possible to use
district cooling. This limits the use to a great extent.
[0005] Another method which has been developed to manage the lack
of electrical power for the cooling machines is evaporative cooling
whereby the ventilation air is cooled by moisturising it with
water. In more advanced plants both the supply and the return air
is moisturised and rotating heat exchangers and driers are also
used. The method may in many cases replace mechanical cooling but
has its limitation in very hot climates or in hot climates with
high air humidity. Air treatment and cooling plants which are used
in this cooling method are mainly in operation only during office
hours.
[0006] Another method which has been developed to manage the lack
of electrical power for the cooling machines is the use of
reservoirs for storage of chilled water coolth or ice coolth
whereby the coolth is stored in water or ice reservoirs to
eliminate the power peaks during office hours, by way of a cooling
machine being operating during non-office hours and cooling the
reservoirs and where the stored coolth then is used to minimize the
operation of the cooling machine during the hours when the
electrical transmission network system is the most loaded. A
problem with the cooling method mentioned above is that a separate
storage plant is needed to buffer the cooling power which is
produced. Another problem with the cooling method mentioned above
is that it is costly and complicated.
BRIEF DESCRIPTION OF THE INVENTION
[0007] The problem with the need of a separate storage device to
buffer cooling power is solved according to the invention by
providing a method for temporary reduction of electrical power
consumption for cooling of buildings according to claim 1.
[0008] As the method for temporary reduction of electrical power
consumption for cooling of buildings comprises the features in
claim 1, the advantage, that an uncomplicated and cost effective
temporary reduction of electrical power consumption for cooling of
a building can be carried out, is obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The invention will be described in more detail below with
reference to the accompanying drawings, where:
[0010] FIG. 1 shows schematically a module-built house in
horizontal section through a story,
[0011] FIG. 2 shows schematically a slab for a module with five
hollow channels (hollow cores) through which supply air can
flow,
[0012] FIG. 3 shows schematically a flow chart for a part of the
building,
[0013] FIG. 4 shows computer simulated cooling powers for the
method according to the invention and the conventional method,
[0014] FIG. 5 shows how an ejector increases the cooling of the
room air.
DEFINITIONS
[0015] Re-circulated room air is defined as within the building
re-circulated supply air and return air without addition of outdoor
air.
[0016] Exhaust air is defined as the air which is leaving the
building through the exhaust air fan.
[0017] Supply air is defined as the air which is conveyed into a
room. The supply air may, if nothing else is mentioned, consist of
either re-circulated room air, re-circulated room air with added
outdoor air or outdoor air alone.
[0018] Cooling power is defined as the power which the cooling
machine emits to the air.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0019] The present invention relates to a method for temporary
reduction of electrical power consumption for cooling of buildings
where the cooling energy is stored in slab or wall, comprising the
steps of: [0020] storing cooling energy in at least some part of
the slab or the wall by means of that, during at least one period
of time when the electrical transmission network system can supply
the necessary electrical cooling machine power, supply cooling
machine cooled supply air to channels arranged in the slab or the
wall, and [0021] during at least one period of time when the
electrical transmission network system is highly loaded reduce the
electrical power consumption of the cooling machine and at the same
time convey supply air through the building through the mentioned
channels, which supply air when entering the channel is warmer than
the surrounding slab surface or wall surface adjacent to supply air
terminal devices, hereby using the earlier in the slab or wall
stored cooling energy to cool the supply air.
[0022] In order to be able to use the invention to a maximum the
ceiling surfaces may not be covered with for example compact false
ceilings which obstruct the absorption in the slab of the energy
generated in the room.
[0023] Conventional office buildings are provided with false
ceilings which are situated at such a large distance below the
supporting slab that the space obtained is enough to house the for
each room necessary supply lines for example for electricity,
heating, cooling, supply air, return air and data, etc. Thereby the
possibility for storage through the ceiling area of the internal
energy generated in the room is efficiently obstructed.
[0024] The slabs may in a known manner consist of prefabricated
hollow core slabs of concrete or concrete slabs with embedded
channels.
[0025] FIG. 1 shows schematically a module-built house in
horizontal section through a floor, more precisely the roof slab,
with a number of underlying rooms A, B and the corridor C. The
rooms A and B are limited by the outer walls 1, the corridor walls
2 and the room-separating walls 3. Each room A consists of three
modules 4 at 3.times.1.2 m each (see FIG. 2) where in each module
three connected channels 5 are run through by supply air from a, in
the ceiling of the corridor C situated connector terminal device 6
and supply air channel 7, which via vertical shafts connects to a
fan room situated on the roof. The supply air from the module 4 is
then flowing through the supply air terminal device 8 into the room
A. The return air from the rooms A goes through a overflow terminal
device in the corridor wall, not shown on the drawing, out to the
corridor which in this case serves as collecting channel, for
further transport to a fan room. The floor slab in room A is used
in the same way as the roof slab for distribution of supply air. In
this case to a room situated below room A. The modules 4 are laid
up on the facade walls.
[0026] FIG. 2 shows schematically a slab for a module with five
hollow channels (hollow cores) through which supply air can flow,
of which according to FIG. 1 three are connected for supply air
distribution.
[0027] FIG. 3 shows schematically a flow chart for a part of the
building, and how those in FIG. 1 and FIG. 2 mentioned modules 4
are connected with the flow chart of the building. Only one module
for each room is accounted for as an example. The equipment for
cooling and air-change of the building comprises a supply air fan
20 and a return air fan 21. Further, a heat exchanger 22, a cooling
battery 23, and four motorised cut-off valves 24, 25, 26 and 27 are
included. The cooling machine 28 supplies the cooling batteries
with, for example cooling water, for cooling of the supply air. Via
return air terminals 29 the return air in the corridor C is
transported (see FIG. 1) back to the fan room.
[0028] The plant operates in the following way: During office hours
the valve 26 is closed and the rotating heat exchanger 22 is in
operation. The fans 20 and 21 are turned on. The other valves are
open. Outdoor air comes in through valve 24, passes the fan 20 and
is cooled through the cooling battery 23 for further transportation
through the slab modules 4 to the different rooms. The return air
is sucked through an return air terminal device located in the
corridor back to the fan room. During non-office hours the fan 20
is in operation. The fan 21 and the heat exchanger 22 are turned
off. The valves 26 and 27 are open. The other valves, 24 and 25,
are closed. Supply and return air now circulates in the plant from
the terminal device 29 via the valve 26 to the fan 20 and is cooled
through the cooling battery 23 via modules 4 again out to the
rooms. This means that the room air is re-circulated in the
building as no outdoor air is added.
[0029] When high electrical power capacity is available, the slabs
are cooled down. As it, during non-office hours, only is room air
which is re-circulated over the cooling batteries, a low cooling
power is required as no outdoor air is added during this time
period. However, the power may be increased by lowering the supply
air temperature a couple of degrees.
[0030] Alternatively, one may use a heat exchanger between the
outdoor air and the exhaust air, preferably with high efficiency,
and after the heat exchange to cool down the supply air to a
required temperature. The cooling machine power and the power
consumption gets higher with this method.
Calculation Example
[0031] Assumptions: A 10 m.sup.2 office room with a facade length
of 3.6 m (3.times.1.2 m module slabs) is situated at a west facade
in a hot climate. The outdoor temperature is maximum 43.degree. C.,
minimum 29.degree. C. The supply air temperature +14.degree. C. Two
persons are in the room between 08-17 hours, and internal power
such as lighting, computers, printers, etc. is 25 W/m.sup.2 during
the same time period. The cooling power of a plant which works
according to the invention is limited to 30% of that of a
conventional mechanical cooling plant between 11-16 hours. Similar
rooms are situated above and below the calculated room. The
calculations have been performed with EQUA's computer program; IDA
Indoor Climate and Energy (ICE).
[0032] If the calculation is performed so that the room temperature
in the office room described above of around 10 m.sup.2 does not
exceed 24.degree. C. and without any cut-down in power, a 30 l/s
larger supply air flow is required in the conventional case
compared to the method according to the invention. In total 70 and
40 l/s, respectively, is needed. The reason for this is that the
plant in the conventional case only is in operation during office
hours and that the larger part of the in the room developed power
must be cooled away directly as it cannot be stored.
[0033] FIG. 4 shows computer simulated cooling powers for the
method according to the invention and the conventional method
during the time period 00-24.
[0034] The electrical power for the cooling machine is normally
around 50% of the supplied cooling power.
[0035] According to the conventional method maximum 1950 W cooling
power is required between 08-11 hours and maximum 2050 W cooling
power between 16-17 hours to hold the temperature requirement of
24.degree. C. Between 11-16 hours the power has been reduced to
1150 W, i.e. around 55% of the maximum power which is 2050 W.
During non-office hours 17-08 hours the cooling machine is turned
off.
[0036] In the conventional case the room temperature has risen at
16 hours to around 27.5.degree. C. Here are thus significant
investments required in costly additional equipment, for example
cooling water reservoirs, to reach the set-up savings effects.
[0037] The method according the invention needs maximum 1100 W
during the time period 08-11 hours and maximum 1150 W between 16-17
hours in order not to exceed the temperature requirement of
24.degree. C. This corresponds to around 55% of the cooling power
in the conventional case. Between 11-16 hours the power is reduced
to 600 W, that is around 30% of the maximum power 2050 W in the
conventional case.
[0038] During non-office hours at 17-08 hours the cooling effect
never exceeds 500 W--which corresponds to a supply air temperature
of around 14.degree. C.--as the room air is only re-circulated in
the building and addition of outdoor air is not required, this
because of that no or very few people are situated in the building
during non-office hours, i.e. during non-working hours.
[0039] From having cooled down the slab with 14.degree. C. supply
air between 16-11 hours (between 17-08 this has taken place with
re-circulated room air without additional outdoor air) the reduced
power consumption during the time period 11-16 hours will give a
supply air temperature of around 22.degree. C. in this case. This
supply air will warm up the slab from within between 11-16 hours at
the same time as the surface layer of the slab has enough cooling
capacity for the room air not to exceed the chosen temperature
limit, in this case 24.degree. C. Thus the slab is warmed up both
from within and from the outside during a limited time period.
[0040] The power requirement (power.times.time), in this case Kwh,
corresponds with the framed areas of the power curves. As both
buildings have the same insulation standard, theoretically the same
amount of power is required during a 24 hour period, but as the
invention uses the cooler night air for cooling of the cooling
machines, a better efficiency is obtained which corresponds to a
power saving of around 10% annually. In the conventional case the
room has false ceilings.
[0041] The operative temperature (=experienced temperature=the mean
value of the room temperature and the temperature on the surfaces
which enclose the room) is lower than the room temperature
according to the invention. As the experienced temperature is lower
than the actual room temperature, it feels cooler than what the
thermometer shows. In the convention case it is the other way
around.
[0042] The reason for the large power and flow reduction according
to the invention depends on a number of co-operating elements:
[0043] The blocking time, that is when the power consumption is
reduced, is limited. The five hours between 11-16 hours cannot be
prolonged more in this example without the room temperature rising
to unacceptable levels, in the calculation example over 24.degree.
C. This depends on the outdoor temperature, the air humidity and
the degree of density in the building, the insulation level, the
re-cycling level of room air, internal powers, etc. During a
shorter time period it is possible to reach larger power savings
than the 70% which have been accounted for in the example without
the room temperature exceeding 24.degree. C. For example the
cooling plant can be closed down completely so that the power is
decreased to zero (0) during two hours.
[0044] The slab as power storage must have enough capacity (mass)
and be able to transport necessary air in the hollow channels. The
slab surfaces, that is the roof and floor surfaces, must be
accessible, that is thick carpets, false ceilings, sound absorbing
baffles, etc. must be installed in a way so that the heat transfer
by convection or by radiation is not hindered to any greater
extent.
[0045] The largest part of the energy developed in the room shall
during the actual time 11-16 hours be transferred to the slab in
order to during the other hours of the day be transported away with
cooled supply air which during non-office hours consists of
re-circulated room air.
[0046] There are a number of alternative embodiments of the now
described method within the scope of the inventive idea to further
reduce the cooling power.
[0047] A conceivable possibility is to reduce the supply air flow
during a shorter time period when the electrical transmission
network system is highly loaded. The air flow shall always be
arranged so that odour from people, building materials, moisture,
etc. does not become troublesome. This corresponds to a minimum air
flow of around 6-10 l/s and person. In rooms with high internal
heat development and/or very hot outdoor climate, the mentioned
supply air flows are not enough, when air cooling of rooms, in
order to meet the comfort requirements. As appears from the example
above, according to the invention, 40 l/s and in the conventional
case 70 l/s, is required to obtain a good indoor climate. If 8 l/s
and person is chosen in the calculated case according to the
invention, this corresponds to 16/40=0.4 times the original flow,
that is 0.6 times lower flow during a shorter time period,
corresponding to 60% lower cooling power during the same time
period. The method according to the invention has, according to
FIG. 4, reduced the power to 30%. If during one hour the flow
and/or the power together are reduced with an additional 60%, the
total power use will now be 0.40 times 30%=12% of the original 2050
W. The assumption here is that a small increase of the room
temperature can be accepted, in this case 0.5-1.degree. C.
[0048] Another conceivable possibility to reduce the cooling
machine power is that, as is shown in FIG. 4, to introduce in the
flooring channels 41 an ejector 42, or a fan with low power, which
through the driving force created by the supply air or the fan
together with it sucks room air 43 which is cooled down in the slab
and after having passed the supply air terminal device 44
contributes to the cooling of the room.
[0049] In the described embodiment slabs have been used for storage
of cooling energy. However, it is also possible that also, or
alternatively, store cooling energy in walls such as inner and/or
outer walls in buildings in a similar way.
* * * * *