U.S. patent application number 13/136252 was filed with the patent office on 2012-01-26 for variable performance building cladding according to view angle.
Invention is credited to Matthew Murray Botke.
Application Number | 20120017521 13/136252 |
Document ID | / |
Family ID | 45492405 |
Filed Date | 2012-01-26 |
United States Patent
Application |
20120017521 |
Kind Code |
A1 |
Botke; Matthew Murray |
January 26, 2012 |
Variable performance building cladding according to view angle
Abstract
This invention relates to inclined outer building surfaces such
as roofs reflectively responsive to sun elevation angle and
predominantly ornamental when viewed from common viewing positions.
More specifically, this invention relates to methods of sizing,
shaping, surface characteristics, and coating resulting in improved
performance, increased ornamental quality, improved economy of
roofing of this class using human eye contrast sensitivity and
visual perception.
Inventors: |
Botke; Matthew Murray;
(Moorpark, CA) |
Family ID: |
45492405 |
Appl. No.: |
13/136252 |
Filed: |
July 25, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61367477 |
Jul 26, 2010 |
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Current U.S.
Class: |
52/90.1 |
Current CPC
Class: |
E04D 1/02 20130101; E04D
2001/005 20130101; E04D 1/16 20130101; E04D 3/30 20130101; E04D
1/2916 20190801; E04D 1/04 20130101; E04D 1/26 20130101 |
Class at
Publication: |
52/90.1 |
International
Class: |
E04B 7/02 20060101
E04B007/02 |
Claims
1. An aesthetically pleasing slanted roof reflectively responsive
to sun elevation angle, comprising; a repeating set of surfaces,
portions of which are oriented predominantly toward the sun and
portions of which are oriented predominantly toward observers at
common viewing positions; and, treatments applied to the surfaces,
comprising; at least one surface treatment that is selected for
emissivity and reflectivity properties in the direct sunlight
direction; and, at least one surface treatment that is selected for
aesthetically pleasing visual properties in the observer viewing
direction, wherein; the surface treatments are selected and applied
to reduce visual perception of the repeating set of surfaces.
2. The roof of claim 1 wherein at least a portion of the surface
treatments are smoothly varied between regions of high contrast
differential.
3. The roof of claim 1 wherein surface treatments are selected to
reduce visible contrast amplitude.
4. The roof of claim 3 wherein at least one surface treatment
selectively reflects non-visible sunlight in the direct sunlight
direction.
5. The roof of claim 1 wherein the surfaces are textured to
increase visible spatial frequency.
6. The roof of claim 1 wherein at least a portion of the surface
treatments are applied in a visible pattern.
7. The roof of claim 1 wherein surface treatments are applied at
the location of use.
8. The roof of claim 3 wherein the contrast reduction includes at
least one of; applying the treatments to the sun facing and
observer facing areas in analogous colors, applying the treatments
to the sun facing and observer facing areas with small luminance
differential, sizing the treatments with dimensions below the
spatial resolution of observers at common viewing positions; and,
applying the treatments with smoothly varying gradients between the
sun facing and observer facing areas.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 61/367,477 filed on Jul. 26, 2010.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable
THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT
[0003] Not Applicable
REFERENCE TO SEQUENCE LISTING, A TABLE OR A COMPUTER PROGRAM
LISTING COMPACT DISC APPENDIX
[0004] Not Applicable
BACKGROUND OF THE INVENTION
[0005] Heat energy transfer through the building envelope changes
the temperature of the interior space and can therefore become
uncomfortable. Energy must be expended to maintain the desired
temperature if this space is conditioned in order to offset energy
transfer to or from the environment. Therefore, minimal energy
transfer across the envelope is desirable. The rate of energy
transfer across the building envelope becomes significant when
large temperature differences exist between the ambient environment
and the interior space. A primary source of heat energy loading on
the envelope is due to the absorption of direct solar radiation.
Characteristics by which the outer surface interacts with incident
solar radiation have significant affect on the heat transfer
between the interior space and the outside environment.
Traditionally, the energy required to cool a conditioned space is
more expensive than the equivalent energy required for heating the
same space due to the type of energy required for each application.
Therefore, buildings located in regions with hot summers benefit
from methods to reject solar heat gain.
[0006] Elevation and azimuth sun angles vary according to date,
time, and the latitude on the earth from which the angles are
measured. Daily peak heating occurs in the hours surrounding solar
noon when the elevation angle of the sun is at or near the daily
maximum. Yearly peak heating occurs at summer solstice when solar
noon sun elevation angle reaches annual maximum. For example,
during summer solstice at 34-deg N latitude, the sun elevation
angle remains above 40-deg for over seven hours. By comparison,
during winter solstice the sun reaches a maximum of only
approximately 35-deg elevation angle at solar noon. Energy used to
cool a conditioned space in the summer most often reaches a maximum
in the early afternoon as a result of the energy absorbed into the
active thermal mass of the envelope throughout the day and
especially during the solar noon hours.
[0007] Energy transfer across the building envelope is affected by
the outer building surface properties. Some relevant properties
are; [0008] a. reflectivity, which herein describes the
non-wavelength dependent total fraction of incident solar radiation
reflected and is measured on a scale of 0 to 1, whereas 1 is a
perfect reflector, and [0009] b. absorptivity, which herein
describes the non-wavelength dependent fraction of incident solar
radiation absorbed and is measured on a scale of 0 to 1, whereas 1
is a perfect absorber, and [0010] c. emissivity, which herein
describes the non-wavelength dependent effectiveness of emitting or
radiating absorbed energy to the surroundings for a given
temperature difference between the cladding and surroundings
assuming optically thick materials and is measured on a scale of 0
to 1, whereas 1 is a perfect blackbody emitter, and [0011] d.
thermal capacitance per unit mass which herein describes the
temperature rise of the materials for a given unit of energy input,
and [0012] e. thermal conductivity, which herein describes the time
rate of heat energy conducted through materials and into or out of
surroundings in physical contact, and [0013] f. surface orientation
and latitude with respect to the earth.
[0014] Absorbed heat energy raises the outer surface temperature of
a building surface in proportion to thermal capacity and thermal
mass of the material in thermal proximity. The absorbed energy is
then typically transferred through conduction and radiation into
the building substrate, re-radiated into the surroundings, and or
transferred through convection to the air. Roofs comprised of low
reflectivity and low emissivity surfaces exposed to solar radiation
will reach a higher peak temperature compared to a similar roof
with higher reflectivity and emissivity resulting in increased
local air temperature. The effects of local air heating in regions
with a high proportion of absorbing surfaces such as in developed
areas is known as the Heat Island Effect. In the past, most high
reflectivity building surfaces have been incorporated into flat
roofs, which typically comprise a large area fraction exposed to
the sun and are not commonly visible. These types of roofs are not
limited by ornamental requirements and most often are white.
Buildings with inclined roofs such as residential structures also
typically benefit from high reflectivity. Since darker colors are
preferred for visible roofs, high reflectivity roofing has not been
widely adopted in residential buildings.
[0015] Building materials and coatings have been developed that
selectively reflect in the near-infrared portion of the spectrum
thereby preserving a traditional appearance while reflecting
approximately 52% of the direct incident solar energy. This method
is effective but limited in efficiency. The visible portion of the
solar spectrum contains approximately 43% of the incident solar
energy and significantly contributes to solar heat gain. Building
performance is substantially improved when integrated with
broad-spectrum reflective surfaces. Since roofs represent the
largest exposed surface to the sun on low-rise buildings,
reflective roofs have a large impact on energy use in conditioned
interior spaces. Building surface incline angles vary from
approximately flat to nearly vertical. Sloped roof incline angles
are generally described as the ratio of vertical rise to 12 units
of horizontal run. Steep slope roofing typically is classified as
between 2:12 and 12:12. The majority of roofs are typically sloped
at between 4:12 and 8:12. What is needed is a method of
economically integrating broad-spectrum reflective surfaces into
roofing applicable to a wide range of slope angles while preserving
traditional appearance.
[0016] Visual perception is a combination of the performance of the
human eye and the synthesis of the visual scene by the brain. The
eye is able to resolve features as a function of contrast to
surroundings and apparent feature size. This contrast sensitivity
function is generally characterized as curve (72) shown in FIG. 7
plotted against contrast amplitude along the vertical axis and
spatial frequency along the horizontal axis. Spatial frequency is
the number of contrast cycles in one degree of subtended angle in
the visual scene. Variations of both contrast amplitude and special
frequency is illustrated as the several sine wave functions (71).
The eye is typically able to resolve features along and under this
curve and with increasing contrast as shown in region (73) and is
typically unable to resolve features in regions (74) and (75).
Visual sensitivity of the human eye reaches a maximum at about 4 to
10 cycles per degree of subtended angle in the visual field
depending on lighting conditions with greater sensitivity
associated with brighter lighting conditions. The eye can generally
resolve features with the minimum contrast in this range of spatial
frequency. Visual sensitivity for a given spatial frequency and
contrast is lower for smoothly varying contrast such as a sine wave
compared to abrupt contrast changes such as a square wave. Further,
the sensitivity curve is not symmetrical around the maximum
sensitivity and decreases more rapidly as spatial frequency
increases. Therefore for a given contrast, visual sensitivity
decreases more rapidly as feature sizes are reduced.
[0017] Achromatic contrast herein is the difference in luminance
between any two points along the spectrum from black to white
through all the shades of grey and can be measured on a scale of 0
to 1 where 1 is maximum contrast such as between white and black.
Chromatic contrast herein generally relates to the contrast between
colors as a function of hue, saturation, and luminance. FIG. 8
illustrates a color wheel in a Red-Green-Blue color model.
Complimentary colors are considered to have high chromatic contrast
amplitude and are located at diametrically opposed points on the
color wheel. Analogous colors are located adjacent to each other on
the color wheel as indicated by (81) and are considered to have
lower contrast and therefore lower contrast sensitivity for a given
spatial frequency. Traditional analogous colors used on a building
surface are typically considered warm colors such as reds. Dark
colored roofs are traditionally preferred and are also typically
from the warm color group or black.
BRIEF SUMMARY OF THE INVENTION
[0018] Sloped roofs such as those typically found on residential
buildings comprise a large fraction of the appearance of the
building to users and also present a large exposed surface to the
sun. Since the view factor of the roof presented to observers
differs from the view factor to the sun essentially throughout the
entire day, the roof can be configured to exhibit different
properties for each such as reflectivity and apparent color. Sloped
roof systems are viewed from below the elevation of the roof from a
generally predictable locus of points, herein referred to as common
viewing positions and is determined by the typical interaction of
people with each particular building. Normal routes of ingress,
egress, commonly accessible areas such as driveways, parking lots,
and lawn areas, as well as views from proximal transit routes such
as streets and sidewalks comprise normal viewing locations from
which the roof of the building contributes to the overall
aesthetics of the architecture. Generally, architectural aesthetics
are most relevant when the observer is in close proximity to the
building. More specifically, common viewing positions herein
relates primarily to observers standing at ground level within
about 60-meters from a building roof. Of course, the observer view
of the roof will vary according to observer location relative to
the roof surface, building height, and roof pitch. The view factor
of the roof to the sun can be determined based on location upon the
earth, roof surface orientation, date, and time of day.
[0019] This invention relates to inclined building surfaces such as
sloped roofs passively reflective to incident solar radiation
according to sun elevation angle having substantially traditional
ornamental appearance when viewed from a wide range of common
viewing positions and applicable to a wide range of building
surface incline angles. A roof according to this invention utilizes
treatments to achieve desirable reflectivity and emissivity
characteristics while reducing contrast sensitivity and visual
impact thereby resulting in a roof that has substantially improved
performance, ornamental quality, and manufacturing economy.
[0020] FIG. 1 illustrates a pitched roof according to this
invention comprised of predominantly sun-facing surfaces (11) and
predominantly observer-facing surfaces (12), wherein predominantly
is taken to mean the orientation of the larger fraction of that
portion of the surface. These two sets of surfaces form surface
features following the contour of the underlying roof extending
generally parallel to the roof ridge (14) and repeating in the
pitch direction from the fascia (13) to the ridge. Sun-facing
surfaces comprise the larger fraction of the view factor of the
roof to the sun at high sun elevation angles (19) such as at a sun
elevation angle of about 30 degrees or higher. Observer-facing
surfaces comprise the larger fraction of the view factor of the
roof to observers at common viewing locations (17). The maximum
view factor to the sun of substantially high elevation angle
sun-facing surfaces increases as the sun elevation angle increases
throughout the day and reaches the daily maximum at solar noon. The
time rate of change of the view factor to the sun is a function of
many parameters including; latitude, roof slope, date of the year,
time of day, and surface profile according to this invention. A
building surface such as a sloped roof according to the present
invention comprising predominantly observer-facing ornamental,
typically darker surfaces and high sun elevation angle sun-facing
reflective surfaces will exhibit a sun elevation angle responsive
composite reflectivity throughout the day with a maximum
reflectivity generally at solar noon.
[0021] Aspects of this invention are presented by which
predominantly sun-facing, predominantly observer-facing, and
transitional interconnecting edge surfaces between sun-facing and
observer-facing surfaces are sized, shaped, colored, coated,
textured, distributed, and or oriented with respect to the visual
perception of observers to achieve applicability to a wide range of
building incline angles while maintaining desirable ornamental
quality and incident solar energy reflectivity. An inclined
building surface according to this invention will exhibit
reflectivity to the sun according to incident angle and similarly
an apparent visible ornamental view to observers at common viewing
locations.
[0022] It is an object of the present invention that gradient
contrast transitions are utilized to reduce the contrast
sensitivity in the visual scene of observers between the
predominantly observer-facing and predominantly sun-facing surfaces
at a given surface profile wavelength.
[0023] These reductions are achieved by any combination of a
variety of treatments applied in such a way as to lie within the
low perception regions of FIG. 7 for an observer at a common
viewing position. One method of achieving contrast sensitivity
reduction is accomplished for example by printing smoothly gradient
patterns, spray coating at an angle, or varying coating thickness
at the edges of the coated surface. Another method of achieving
contrast gradient is accomplished by smoothly varying the shape of
transitional surfaces between sun-facing and observer-facing
surfaces such as by relatively large, generally rounded
interconnecting edge surfaces resulting in a dithered appearance
along the pitch direction of the roof. It is also an aspect of the
present invention that both apparent color, luminance, and or hue
gradient as well as dithered edges may be combined resulting in
gradual contrast transitions and therefore lower visual perception
of predominantly sun-facing surfaces for a given surface profile
wavelength.
[0024] It is another object of the present invention that contrast
amplitude be reduced at a given surface profile wavelength
resulting in desirable ornamental quality while still maintaining
desirable incident solar energy reflectivity performance. Reduced
contrast amplitude is accomplished for example by selecting a
suitable apparent contrasting coating treatment for predominantly
sun-facing surfaces compared to predominantly observer-facing
surfaces. A suitably selected shade of gray coating for
predominantly sun-facing surfaces provides perceptibly acceptable
low contrast amplitude when compared to dark black predominantly
observer-facing surfaces yet still provides increased reflectivity
compared to a uniformly dark black roof. Analogous colors as a
combination of hue and saturation of approximately equivalent
luminance provide perceptibly acceptable contrast sensitivity
between predominantly sun-facing and predominantly observer-facing
surfaces as a result of lower contrast amplitude. It is also an
aspect of the present invention that luminance, hue, and saturation
in any combination are utilized to achieve suitably low contrast
amplitude between predominantly sun-facing and predominantly
observer-facing surfaces resulting in desirable ornamental quality
and incident solar energy performance. It is a further aspect of
this invention that surface finish such as gloss is also utilized
to reduce the apparent contrast amplitude of a roof according to
this invention for a given lighting condition. Therefore, a roof
according to this invention with low contrast amplitude between
sun-facing and observer-facing surfaces may be more economically
manufactured at larger surface profile wavelength and still
maintain acceptable ornamental quality, solar reflectivity
performance, as well as wide building surface incline angle
applicability.
[0025] It is a further object of this invention that texture be
utilized to reduce contrast sensitivity and add visual variety
resulting in increased ornamental quality of a roof reflectively
responsive to sun elevation angle. Texture as it relates to
physical surface roughness may be utilized in any size range
relative to the wavelength of the generally repeating surface
profile of a roof according to this invention. A preferred texture
size range is from approximately less than 0.010 times the profile
wavelength of predominantly sun-facing and surfaces to greater than
10 times the profile wavelength. A more preferred range of texture
is from approximately 0.1 times the profile wavelength to 1.0 times
the profile wavelength. Roofing granules, sputtered paint textures,
and discontinuities in predominantly sun-facing and observer-facing
surfaces are but a few examples of texture within the preferred
size range.
[0026] It is yet a further object of this invention that patterns
of features be utilized in any combination of visually perceptible
artifacts such as contrast, color, physical feature
characteristics, texture, and or surface finish that are arranged
within a surface, on a surface, or extending across more than one
surface in any combination of repeating or random spatial
relationship to reduce contrast sensitivity of the repeating set of
predominantly sun-facing and predominantly observer-facing
surfaces. Features and patterns of features provide elements in the
visual scene that add architectural interest, simulate natural
materials, or provide greater relative visual significance
resulting in a reduction of visual perception of the predominantly
sun-facing surfaces.
[0027] It is even a further object of this invention that
combinations of size, shape, color, surface finish, texture,
distribution, and or orientation be used on inclined building
surfaces substantially ornamental when viewed from common viewing
positions and reflectively responsive to sun elevation angle
resulting in desirable incident solar energy reflectivity
performance. An example of reduced impact in the visual scene of
predominantly sun-facing surfaces results in a generally uniform
apparently lighter color than the color of the predominantly
observer-facing surfaces alone when viewed from typical viewing
positions. A roof according to this invention having perceptually
visible delineation between predominantly sun-facing and
predominantly observer-facing surfaces remains desirably ornamental
by use of texture, pattern, color choice, and contrast gradient
typically within an order of magnitude on the contrast sensitivity
curve to visible delineation contrast and spatial frequency.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0028] FIG. 1 is a perspective view of a roof system according to
this invention
[0029] FIG. 2 is a perspective view of a shingle according to the
present invention.
[0030] FIG. 3A and FIG. 3B are sectional views of the shingle
illustrated in FIG. 2.
[0031] FIG. 4 is a perspective view of a metal panel according to
the present invention.
[0032] FIG. 5 is a perspective view of a flat tile according to the
present invention.
[0033] FIG. 6 is a perspective view of an s-curve or Malibu tile
according to the present invention.
[0034] FIG. 7 is a chart illustrating the contrast sensitivity
function of the human eye.
[0035] FIG. 8 is a chart illustrating a color wheel using the
Red-Green-Blue color model.
[0036] FIG. 9 is a chart illustrating a representative reflectivity
curve as a function of observation angle according to this
invention.
DETAILED DESCRITPION OF THE INVENTION
[0037] An inclined building outer surface reflectively responsive
to sun elevation angle is disclosed having high ornamental quality
over a wide range of common viewing positions and applicable to a
wide range of incline angles. In embodiments according to the
present invention, surfaces are adapted to appear with non-constant
and perhaps continually varying contrast and or reflectivity across
surfaces for a given surface profile wavelength based on the human
eye contrast sensitivity function and visual perception. An
inclined building outer surface according to this invention
therefore has wide applicability to a large range of roof slopes
thereby increasing cost-effectiveness, reducing visual impact of
surface profiles, and simplifying installation while maintaining
acceptable energy performance. Embodiments of the present invention
are currently contemplated as tiles, panels, shingles, membranes,
granulated roll roofing and other materials known to be suitable
for use on inclined building surfaces including and especially
materials used for sloped or pitched roofing.
[0038] Methods of accomplishing this invention during or after
installation on a building are also contemplated. As but one
example is a process by which physical features are embossed and
then selectively spray coated resulting in a building surface
responsive to sun elevation angle and ornamental when viewed from
common viewing positions. Embodiments disclosed herein illustrate
many of the various aspects of the invention and are not intended
to be scope limiting to specified attributes such as feature sizes
or ratios, coating selection, construction, materials and the like.
Further, aspects disclosed may be combined in any way and not
depart from this invention.
[0039] A first contemplated embodiment is illustrated in FIG. 2 as
a tabbed asphalt shingle. Exposed regions of the shingle such as
the tabs (24) have an exterior profile comprised of predominantly
sun-facing surfaces (22) and predominantly observer-facing surfaces
(23). Unexposed surfaces such as the top lap portion of a shingle
(21) do not require surfaces according to this invention and may be
of traditional design including a heat-activated adhesive asphalt
strip (25). A partial side view of the shingle shown in FIG. 2 is
illustrated in FIG. 3. FIG. 3A illustrates the typical components
of an asphalt shingle according to this invention including an
asphalt-saturated base material (32), stabilized asphalt weathering
layer (34), and mineral or ceramic granules (33). A series of
ridges (31) integral to the shingle comprise predominantly
sun-facing surfaces (35), predominantly observer-facing surfaces
(37), and interconnecting transitional edge surfaces (36) and (38).
As but two examples of methods of forming the ridges are by
embossing or roll forming the weathering asphalt and granulated
layers at acceptable temperature and pressure. Transitional
surfaces smoothly transition the exposed roof surface from
predominantly sun-facing to predominantly observer-facing
surfaces.
[0040] FIG. 3B describes some of the relevant shape characteristics
of a roof surface according to this invention. Surfaces exposed to
the environment generally repeat along the pitch direction of the
inclined building substrate at a profile wavelength (311) and
amplitude (39).
[0041] Predominantly sun-facing (35) and predominantly
observer-facing (37) surfaces are oriented at angles to the
horizontal plane (313) and vertical plane (312) respectively.
Predominantly sun-facing surface orientation with respect to the
horizontal plane may be tilted for rain shedding either toward or
away from the pitch direction of the roof. Reducing the amplitude
and also generally proportionately the wavelength of the repeating
set of surfaces results in a desirably reduced spatial frequency
and therefore the visual perception of the surfaces when viewed
from common viewing positions. A preferable range of repeating
surface set size is within about the range small enough to be
nearly imperceptible to observers at common viewing positions yet
large enough for economical manufacture. Feature sizes greater than
about 4-mm with rain shedding tilt angles away from the pitch
direction of the roof generally require methods of precluding
degrading amounts of water pooling and subsequent infiltration.
Surface features smaller than about 4-mm and approaching the
surface roughness of traditional roofing such as granulated roofing
typically shed water acceptably well so as not to degrade the life
of the building material. In all size ranges, the length of
continuously extending surface ridges especially with predominantly
sun-facing surfaces oriented with a tilt angle away from the pitch
direction of the roof should be limited to provide the most
expedient drainage method for high rates of precipitation. In order
to achieve acceptable rain shedding and drainage, surface features
such as discontinuities, notches, breaks, the distribution of
surfaces, distribution of feature sizes, surface orientation, and
surface texture may be utilized in any combination. FIG. 2
illustrates a discontinuity (26) in the surface features according
to this invention.
[0042] Granulated asphalt roofing materials with a weathering layer
of stabilized asphalt have a traditional range of layer thicknesses
and distribution of granule sizes, which largely determine the
range of amplitude and cycle wavelength resulting in acceptably
well-formed surfaces according to this invention. Granulated
surfaces at this range of amplitude and profile wavelength result
in a textured surface with reduced contrast sensitivity by
effectively increasing spatial frequency above or within acceptable
proximity to curve (72). A preferred amplitude and cycle wavelength
is within 1-mm to 8-mm. Even more preferable is an amplitude and
cycle wavelength of about 2-mm and 4-mm respectively. Surface
features within this size range result in a texture (33) including
randomly distributed surface notches thereby further reducing
contrast sensitivity and enhancing water shedding.
[0043] Another contemplated embodiment of the present invention is
illustrated in FIG. 4 as a metal panel. Predominantly sun-facing
(42), predominantly observer-facing (43), and transitional
interconnecting edge surfaces (47) and (48) are formed in sheet
metal. Coatings may be applied before and or after forming steps.
Methods for assembling the panel into a contiguous weather
resistant cladding such as a head-clip (42) and a lower tab (41)
are well known. Similarly, horizontally adjacent panel joining
methods are well known for cladding of this class such as by
integral vertical side flanges for standing seam systems.
[0044] For either roof type, for a given profile wavelength and
amplitude of generally repeating surface features according to this
invention, contrast sensitivity is reduced by smoothly
transitioning between surfaces of maximum contrast such as by
gradients on sun-facing surfaces (44), observer-facing surfaces
(45), and or on transitional interconnecting edge surfaces (47) and
(48). Gradients are typically accomplished by varying luminance and
or hue and saturation smoothly through one contrast cycle, which is
equivalent to the repeating surface profile wavelength (311).
Methods of accomplishing gradients include varying the coating
opacity by varying coating thickness or dithering the coating
edges. Contrast sensitivity is also reduced according to this
invention for a given surface profile amplitude and wavelength by
reducing the maximum contrast amplitude when viewed from common
viewing positions Techniques, which may or not include smoothly
varying gradients include applying the treatments to the sun facing
and observer facing areas in analogous colors, with small luminance
differential or both. Contrast reduction techniques also include
increasing spatial frequency by reducing surface profile amplitude
and wavelength treatments to about or more preferably below the
spatial resolution of observers at common viewing positions. Or any
combination of techniques with and without smoothly varying
gradients may be employed. It should be understood that the
treatments and surface features disclosed are shown in embodiments
but are amenable to any roofing system suitable for use as an
inclined roof The aspects of the invention may be combined in any
way and may also be effectively utilized individually. Particular
combinations of techniques generally depend on manufacturing
methods, materials, as well as roofing system design. Detailed
examples are presented below. Multiple examples of roof types are
shown, all of which as well as others not shown can benefit from
the invention
[0045] For example, maximum contrast amplitude may be reduced by
using a light gray coating instead of a bright white coating on
predominantly sun-facing surfaces. Contrast amplitude using a
bright white predominantly sun-facing surface compared to the
desired ornamental appearance of predominantly observer-facing
surface might be visually perceptible at a given spatial frequency
such as at point (76) in FIG. 7. A suitably light gray
predominantly sun-facing surface results in an inclined building
outer covering appearing significantly more uniform such as
represented by point (77) in region (75) above the contrast
threshold sensitivity curve.
[0046] Maximum contrast amplitude can also be reduced by selecting
a coating of similar hue and saturation having increased luminance
for predominantly sun-facing surfaces compared to predominantly
observer-facing surfaces. Similar hue and saturation is preferable
within about 45-degrees of arc on the color wheel in FIG. 8 from
the hue and saturation of the predominantly observer-facing
surfaces with which contrast amplitude is determined such as within
arc segment (81) for Red.
[0047] Further, visual appearance can be varied within surfaces and
across surfaces to establish visual impact and interest thereby
reducing the relative visual perception and impact of transitions
from predominantly sun-facing and predominantly observer-facing
surfaces. Patterns may be comprised of any combination of visible
artifacts such as aspects of color, texture, or surface finish. As
but one example of accomplishing variable appearance on an inclined
building surface according to this invention is by printing
patterns (46) during the coating process or as a secondary process.
Visual perceptible impact of surfaces and coatings according to
this invention is more effectively reduced by incorporating
patterns using visual contrast having spatial frequency similar to
the surface profile wavelength. Patterns may be applied to
predominantly observer-facing, predominantly sun-facing,
transitional interconnecting surfaces or any combination of
surfaces. Patterns that visually extend beyond individual surfaces
have visual impact and reduce sensitivity to the generally regular
periodicity of surface profiles according to this invention.
Apparently random or pseudo random and or repeating patterns are
utilized to reduce the visual impact of transitions between
predominantly observer-facing and predominantly sun-facing surfaces
in the scene of persons viewing the building surface from common
viewing positions.
[0048] A third contemplated embodiment of the present invention is
illustrated in FIG. 5 as a concrete or clay roof tile. Tiles are
generally molded or extruded in various profiles. Methods and
features for assembling the tile into a contiguous weather
resistant cladding such as a gutter (57), side lap (58), and head
lap (59) are well known. Predominantly sun-facing (52),
predominantly observer-facing (53), and transitional
interconnecting edge (54) and (55) surfaces have natural
discontinuities for rain shedding at each side of the tile (56).
Notches or grooves (51) in the face of the tile both enhance water
shedding and provide visual impact thereby reducing visual
sensitivity to surface profiles according to this invention.
[0049] Molded or extruded tiles are typically manufactured with
integral color and then coated to inhibit water absorption and
environmental fouling. According to the invention, predominantly
sun-facing surfaces may be further coated with desirably reflective
and emissive coatings. Suitable coatings such as epoxy or urethane
paints with suitable pigment can be applied directly on the tile
using conventional methods such as by spray coating. Predominantly
observer-facing surfaces are suitably functional and acceptably
ornamental as molded. Natural or enhanced color and texture
variation further enhances ornamental appeal across the cladding.
Increasing solar absorptivity of the predominantly observer-facing
surfaces to preferably greater than 0.40 enhances wintertime solar
gain.
[0050] A fourth contemplated embodiment of the present invention is
illustrated in FIG. 6 as an S-shaped tile such as a Malibu tile.
Surface features according to this invention are integrated into
the tile surface (61) following the contours of the tile.
Predominantly sun-facing and predominantly observer-facing surfaces
of sufficiently small size and contrast amplitude remain
sufficiently ornamental. Rain shedding is accommodated by smooth
gutter surfaces (62) between contours resulting in discontinuities
that enhance drainage.
[0051] FIG. 9 illustrates representative reflectivity curves for an
inclined building surface according to this invention. Each curve
smoothly varies according to viewed angle from a low reflectivity
reference (91) to a high reflectivity reference (92). The low
reflectivity reference value is determined by the desired surface
properties of the predominantly observer-facing ornamental surfaces
(12) while the high reflectivity reference value is determined by
the desired surface properties of the predominantly sun-facing
surfaces. Ornamental quality generally correlates to reflectivity
as it relates to darker apparent colors commonly favored for
roofing.
[0052] FIG. 9 illustrates a representative reflectivity curve (93)
according to this invention as a function of the elevation angle
from approximately zero degrees (98) to approximately 180 degrees
(99) looking along the pitch direction of the roof. A view angle of
45-degrees represents a view factor to a roof inclined at 12:12
pitch whereby the look angle is parallel to the horizontal plane.
This view factor is considered an approximate upper bounding limit
within which acceptable ornamental quality should be maintained as
shown in FIG. 9A as point (97). The normal viewing angle for roof
slopes less that 12:12 and or look angles greater than zero with
respect to the horizontal plane result in an elevation angle less
than 45-degrees and the visible reflectivity value will be to the
left of point (97) on curve (93) within zone (94). Acceptable
ornamental quality is desirable within about this range of look
angles as well as high reflectivity at approximately 90-degrees and
greater as shown as zone (96). The shape of the curve within the
transitional zone (95) may be adapted for climate zones or other
factors by varying surface treatments according to the invention.
Therefore, a roof according to this invention with slowly changing
reflectivity at low elevation angles results in a wide range of
viewing positions resulting in high ornamental quality while
maintaining acceptable solar energy reflecting performance.
[0053] The foregoing description of the embodiments of the present
invention has shown, described and pointed out the fundamental
novel features of the invention. It will be understood that various
omissions, substitutions, and changes in the form of the detail of
the systems and methods as illustrated as well as the uses thereof,
may be made by those skilled in the art, without departing from the
spirit of the invention. Consequently, the scope of the invention
should not be limited to the foregoing discussions, but should be
defined by appended claims.
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