Showing results 1 - 179 of 179
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Example of the advanced framing technique, double-stud wall cavity, which will later be filled with blown insulation
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These folding louvered porch doors provide effective shade from low-angle east and west sunlight and can open for views; the photovoltaic panels overhead allow in filtered natural light
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A 5,000- 6,000 Btu/hr air conditioner drawing about 500 watts can be installed in one window of a designated cool room (it is important that the installation is insulated and well-sealed
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A battery storage system can provide reliable back-up power during a grid power outage
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A cool roof utilizes materials with high solar reflectance and thermal emittance to reflect solar energy and reduce heat gain to the home
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A cool room should have low enough heat gains to be easily cooled by a small single-zone cooling system such as a mini-split or a window air-conditioner as shown here
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A Corsi-Rosenthal Box is a highly effective DIY air cleaner made of easy to obtain materials such as HVAC filters, a box fan, cardboard, and tape
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A dense concentration of buildings and pavement can create the Urban Heat Island Effect, where local temperatures can be several degrees higher than the surrounding areas
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A mini-split air-conditioning system can be a highly effective low-energy approach to provide cooling to one designated zone in the house
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A professional tree survey should be made prior to construction to assess the health and usefulness of each tree surrounding the future home and to determine which trees on a building site should be preserved.
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A reversible window fan can operate via thermostatic or remote control and can selectively exhaust air or bring in outdoor air
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A screened-in porch will protect windows from rain, provide shade, and allow more airflow through windows than window screens would
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A shallow, open floor plan allows free flow of cross ventilation through the house
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A typical Las Vegas hot-dry climate home made of wood frame construction and insulated with R-25 expanded polystyrene externally over a drainage plane, with an unvented wood frame insulated attic and roof assembly.
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A variety of battery-powered fans can be used for a cool room without electric power; most charge off a USB charger so they can be solar charged
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Air speeds generated by a typical ceiling fan are in the ideal range for providing occupant cooling without causing disruption
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Airflow can be directed across thermal mass in the ceiling, floor, or elsewhere inside the home through various window and louver configurations
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All populated regions in the United States can experience an extreme heat event, whether northern or southern, humid or dry, or urban or rural
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An innovative U-shaped heat pump offers SEER 15 efficiency and operation with smart phones
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An NFRC glazing system energy performance label will report U-factor, solar heat gain coefficient, visible transmittance, and air leakage; if the window is ENERGY certified, the ENERGY STAR label will be located next to the NFRC label
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Annual average temperatures have increased across North America when comparing the present day to the first half of the last century, and are projected to increase for mid-century and end-of-century relative to the near-present
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Architectural shading can include large eaves, a porch roof, a well-designed pergola, or other building elements
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Calculate projection factor (PF) by dividing overhang (A) by length of window (B).
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Casement windows or wing walls can create zones of higher pressure (right) and lower pressure (left) to encourage cross ventilation when wind is flowing parallel to window openings
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Ceiling fans can be used to aid a night flush strategy by helping to cool down wall and floor surfaces more thoroughly at night, and by providing comfort ventilation during the day
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Clerestory windows bring light in from above, reflecting it off of surfaces, making it more appealing than the direct light that comes from skylights
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Comfort ventilation focuses on airflow over occupants; in this example of wind-driven cross ventilation, the air is directed through the main occupied areas of the bedroom
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Cool towers like this one at the Zion National Park Visitor Center can provide cooling to a building without any energy consumption
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Create a cool room to shelter from extreme heat by selecting a room in the basement or on the north or shaded side of the house, air sealing and insulating, providing low-wattage and battery-operated cooling, and reducing interior heat loads.
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Dense hedges can encourage cross ventilation (left image) or not (right image) depending on how they are placed relative to windows
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Density, specific heat, and volumetric heat capacity (in metric and in English units) of various construction materials
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Double fan window units can have multiple operational modes; most often outdoor air will be brought in at night when outdoor conditions are cooler
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Ducted whole-house fans should be installed with the duct curved and the fan suspended from rafters to reduce noise and vibration transmission to the living area.
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Earth tubes buried in the ground can provide pre-cooling of ventilation air or primary cooling if designed deep and long enough
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East- and west-facing walls receive significantly more sun than north- and south-facing walls in the summertime
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Evaporative coolers use a fan to draw outside air through a wetted pad which cools and humidifies it
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Evaporative cooling is most appropriate in areas where the summer design mean coincident wet bulb temperature is less than 70°F, shown in purple here and labeled as region “A”
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Even when wind is blowing parallel to a wall, an open casement window can create a zone of higher pressure near the window opening, driving airflow into the house
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Example of an earth-sheltered home in hot climate Tempe, AZ uses the cooling properties of the ground to decrease cooling costs
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Exterior shading devices such as awnings or overhangs can significantly reduce cooling loads
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External solar screens are an effective way to reduce solar heat gains through windows while maintaining view.
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Extreme weather, such as wind, fire, flood, or extreme heat (included in the Severe Weather category above) causes most large electric disturbance events in the U.S (defined as affecting at least 50,000 customers) (data from 2000-2016)
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Having both low and high ventilation openings is necessary to promote airflow from the stack effect
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If a cool room is directly under an attic or roof, having lighter colored roofing (home on left) will reduce heat gain to the space as compared to darker roofing (home on right) because the temperature of the roof will be lower (see thermal image)
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In hot climate zones, shade building surface with vegetation for passive cooling.
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In hot, dry climates, passive cooling should focus on shading, night flush through cross ventilation and whole-house fans, potentially using high-mass construction
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In hot, humid climates, passive cooling should focus on shading, airflow through cross ventilation and ceiling fans, and low-mass construction
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In midsummer, the roof and skylights will receive much more solar radiation per square foot than an unshaded east- or west-facing wall, which in turn will receive more solar energy than north- or south-facing walls
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In the middle of summer, the sun shines most directly on the east and west sides of a house, while in winter it shines mostly from the south.
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Inducing airflow through the stack effect requires low inlets and high outlets such as a ridge hood or crown monitor
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Infrared photometry shows the impact of a roof overhang on the south façade of a home, where the unshaded patio stonework is significantly hotter than the shaded portions of the patio and wall surfaces (temperature scale shown is in Celsius).
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Installing an ENERGY STAR ceiling fan is a low-energy way to improve comfort in a designated cool room
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Interior window attachments such as these light-filtering roller shades can reduce heat gains while providing pleasant, diffuse natural light.
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Keep mulch away from trunk of the tree to allow air circulation at the root collar.
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Landscape trees and shrubs to funnel cooling breeze towards a home in hot climate zones.
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Landscaping and Bahama shutters can provide important shade for a designated cool room
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Large deciduous trees provide heat-blocking shade to the walls and windows of this house.
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Leave the soil level around an existing trunk as is (left); do not increase soil height (center) or remove soil in the root zone (right).
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Light colors have been used on exterior walls and roofs to keep buildings cooler in hot climates for centuries, as shown by this traditional building in Morocco, built in the early 1800s
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Light-colored roofs and walls and deep overhangs for shade are some of the features used by builders in the hot-humid climate (Source: Alys Beach Construction).
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Locating windows on adjacent and opposite sides of the house will allow cross ventilation regardless of wind direction
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Low perimeter to area (P/A) ratio home designs reduce heat transfer and perform better in hot climate zones than high P/A ratio homes.
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Multi-layer honeycomb cellular shades such as these can provide summertime energy savings by blocking and reflecting solar heat, as well as wintertime energy savings by providing added insulation.
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Natural ventilation can be wind-driven (cross ventilation) or buoyancy-driven (stack ventilation)
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Passive cooling techniques can reduce or eliminate the use of air conditioning and can be used for backup cooling during emergencies.
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Pleated blinds provide cooling savings in summer by blocking and reflecting sunlight, while allowing some diffuse daylight to pass through.
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Porch roofs, pergolas, and large overhangs can effectively shade windows and doors facing south, southeast, southwest, or even due east or west for most of the day if the overhang is very deep and sufficiently wide.
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Portable air conditioners offer flexibility with where they are located, but usually need to be installed near a window as they require one or two intake/exhaust ducts connected to the exterior
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Reduce thermal bridging in hot climate zones by using an intersecting exterior wall framing technique as shown here.
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Right - Covered porches protect the south-facing windows and doors of this building from solar heat gain.
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Right - Dense vines growing on a covered trellis along the west side of this home provide effective shade for the wall and windows and create a shaded, protected walkway and outdoor seating area.
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Right - In cooler climates, landscape shading should focus on the east- and west-facing walls, while leaving the south side of the house clear for solar access in winter (well-sized roof overhangs could provide summer shading for the south-facing windows)
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Right - These interior solar screens help control glare and solar heat gain while maintaining view to the outside.
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Right - These retractable awnings provide shade to this outdoor living space and reduce heat gain and glare within the home.
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Right - This builder preserved the trees around this new urban-infill home, providing excellent shading in the summer.
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Right - This house has key features to block heat such as such as tree shading for the west wall and roof, minimized west-facing windows, and a porch roof, floor, and wing walls creating deep architectural overhangs and fins to shade south-facing windows
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Right – Deep overhangs, pergolas, and covered entryways minimize heat gain in this commercial building in the hot-dry climate.
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Right – deeply inset entryways and overhangs provide shade to reduce solar heat entry to this building.
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Right – Horizontal overhangs on this house block sunlight in the summer while allowing it in during winter
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Right – Strategically placed trees provide shade to the south-facing windows of this building.
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Right – the building on the right employs light-colored walls, deep tinting, and deeply recessed windows to minimize solar heat gain
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Right – The canopy of this tree is high enough to allow views out the windows of this home while providing excellent shade to walls, windows, and roof.
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Right – The insulation has been located to the exterior of the thermal mass in this wall section
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Right – thermal mass walls, small windows, and recessed porch and trees on the south side of this southwest home help to minimize solar heat gain.
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Right – this commercial building employs good techniques to resist solar heat gain: awnings and pergolas over windows, recessed windows and entryways, deep tinting on glass, and shade plants.
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Right – This home uses a light-colored exterior wall to reduce solar heat gain
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Right – This home uses light tan stucco and white trim to reduce solar heat gain.
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Right – This metal roof is being coated with a cool (high SRI) coating to reduce solar heat gain
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Right – This model home for the Solar Decathlon competition incorporates vertical trellises and retractable exterior blinds to control solar heat gain.
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Right – This shrub has been pruned to allow views out the windows of this home while providing shade to walls, windows, and roof.
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Right – This tree shades walls, windows, roofs, and grounds for two adjacent homes.
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Right- Landscaping shades the entry on the south west corner of this hot dry climate building.
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Right: This house plan orients broad building surfaces away from the west and east, trees are used to shade the west and east, and large overhangs shade windows on the south wall
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Seven categories of exterior window shading attachments, identified on the DOE Efficient Window Coverings website.
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Shade trees planted on the east or west sides of a house are one of the most effective measures that can be taken to reduce heat gains
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Sheer shades can provide very effective daylighting and glare control while maintaining a softened view to the outside
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Side by side comparisons of standard roofing colors (top row) and cool colors (bottom row) shows that solar reflectance (R) can be reduced significantly using special coatings with almost no change to the color
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Small, battery-powered evaporative coolers can be appropriate for personal cooling in arid climates (only)
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Some whole-house fans are equipped with an automatic drop-down cover to provide an air seal at the ceiling level when the fan is not in use
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Some whole-house fans use an automatic insulated cover achieve high R-values when the fan is not in use
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Sources of heat gain in a house include solar gains, infiltration, conduction through walls and roof, occupants, and internal equipment
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Sources of heat gain in a house include solar gains, infiltration, conduction through walls and roof, occupants, and internal equipment
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Sun paths through the sky in winter, spring, summer, and fall show that a home receives the most sun from the south in the winter and from the east/west in the summer
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Tall annuals, like the sunflowers in this picture, can provide very effective shade in summer (left), provide a pleasant view from inside (right), and allow sun into the home in winter when the plants die back.
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Temperatures in deep undisturbed soil at a given location are approximately equal to the annual average air temperature for that location
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The cool shingles on the right have been coated with a ceramic coating to reflect near-infrared radiation, resulting in a cooler roof as shown by these thermal images (red and yellow are hotter, green and blue are cooler).
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The design of this home incorporates multiple methods to reduce summertime solar gains including roll-down exterior blinds, wide exterior horizontal louvers, minimized east/west-facing windows, and vegetation.
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The DOE Efficient Window Coverings website identifies twelve categories of interior window shading attachments.
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The Efficient Window Coverings website allows direct comparison of various window attachment types based on thermal, visual, functional, and installation and durability criteria.
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The existing dark tile roof on this home (top photo) was covered with a light -colored coating on day 6 (middle photo), resulting in a significant reduction in attic temperature and cooling energy consumption (bottom)
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The frequency, duration, and intensity of extreme heat events have increased every decade since the 1960s
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The IR image on the right shows the sun is heating the southeast-facing wall of this concrete-block house to 36C (97F); this corner of the home would not be a good place for a cool room due to lack of shading and insulation
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The light-colored exterior roll-down shades on this building, and the shaded entryway provide very effective control of solar heat gain
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The number of days per year that the temperature exceeds 90°F is expected to increase throughout the contiguous U.S. when comparing mid-century (2036-2065) to near-present (1976-2005)
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The operable windows in this house are located at occupant level to provide comfort ventilation.
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The patio roof on this home provides full shade to large glass doors and windows, reducing the home's heat gains.
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The south face of this home has an overhanging second floor, a pergola, and a roof eave to provide effective window and door shading for both floors in the summer without blocking view, diffuse daylighting, breezes, or ingress/egress
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The standard asphalt shingle roof on this Florida home readily absorbs solar energy, allowing it to heat up to 140°F (60°C) as shown in the thermal image on the right
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The thermal image on the left and normal picture on the right show the cooling effect of a shade tree on walls and ground surfaces as compared to unshaded areas of the property (darker colors are cooler while lighter colors are hotter in the left image).
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The USDA Plant Hardiness Zone Map can be a valuable reference in determining appropriate landscape plants for your climate .
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The white TPO membrane roof on the row house on the right performs extremely well at reflecting solar energy and maintaining cool surface temperatures while the black EPDM membrane roof on the left heats up rapidly in the sunlight
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The window awnings on this house provide a simple but very effective way to reduce solar gains while still allowing view, daylight, and ventilation through the windows
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There are many landscaping strategies that can be used to reduce the cooling load and energy consumption of a home and its neighborhood.
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There are multiple options for exterior shading of east and west facing glazing systems to avoid direct beam radiation
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Thermal mass causes a time lag in the transfer of heat as well as a dampening of peak temperatures, as shown by this plot
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These aluminum Bahama shutters shade west-facing windows from afternoon sun and are approved for hurricane protection
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These trees were planted between the sidewalk and the street, providing shade to homes, pedestrians, parked cars, and the street.
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This depiction of a saddle installed window heat pump does not obstruct window use and provides fairly quiet 120 Volt operation
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This diagram provides a more realistic view of how a typical direct evaporative cooler operates
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This experimental earth tube is 220 ft long, 8 inches in diameter, and is buried 10 feet deep
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This experimental radiative/evaporative hybrid cooling system uses water to reject heat at night through radiation and evaporation
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This heat pump water heater has been fitted with ducts to exhaust its waste cooling into the occupied living area
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This home uses light-colored standard paints and finishes on siding and roofing materials to reduce cooling loads without adding material cost.
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This hot climate zone home uses high quality batt insulation between studs to insulate this connecting garage wall.
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This hot climate zone home uses high quality batt insulation to insulate truss-joist headers.
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This house is sited so the existing trees will shade the west-facing walls to minimize summertime heat gain
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This infrared image shows little heat gain from north-facing double-pane windows with blinds, but significant heat output from computer monitors
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This MSHP operates with 120 volts power, has an EER of 18 Btu/Wh, uses about 800 W at full output, and operates remotely with a smart home control system
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This room has several passive and low-energy cooling features including a ceiling fan, fully operable French doors, window shading, an outdoor water feature, and light-colored hard-scaping.
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This search for metal roofing products on the CRRC Rated Roof Products Directory highlights the initial and 3-year aged SRI values for each product
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This simplified decision tree can help a homeowner or contractor assess how appropriate a cool roof or wall will be for a particular home
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This wall and window assembly has excessive framing around the windows, which can lead to heat gain in how climate zones.
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This whole house fan is suspended from rafters and connected to the intake grille by a curved insulated duct, greatly reducing vibration and noise in the occupied space
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This whole-house fan is suspended from rafters and connected to the intake grille by a curved acoustic duct, greatly reducing vibration and noise in the occupied space
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Use a truss joist header assembly as shown here to reduce thermal bridging in hot climate zones.
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Using outdoor misters or spray fountains can cool the outside air before it enters the house
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Using roof and wall materials with a high Solar Reflectance Index (SRI) will reduce heat gains.
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Vertical trellises and tall shrubs provide very effective shading to the east-facing wall of this home.
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Vines growing on vertical trellises, along with tall shrubs, provide very effective shade for the east side of this house.
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Wall surfaces having high solar reflectance and high thermal emittance will remain cooler when exposed to direct sunlight.
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When averaged over several years, more fatalities are caused by extreme heat than by any other weather-related hazard
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When preserving a tree, construct a temporary fence around the tree canopy and post signs to keep out vehicles that might compact soil and construction waste that could contaminate the soil.
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White walls and roofs; overhangs and awnings; and operable shutters and garden walls all help to keep out unwanted solar heat gain providing cool interiors for this Florida home.
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Whole-house fans draw outside air through windows into the home and exhaust it into a vented attic
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Whole-house fans or wind-driven cross ventilation can be used to draw air across thermal mass for a night flush strategy
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Wrong - this building provides no overhangs, minimal window shading, and clear window glass resulting in high solar heat gain.
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Wrong – The south side of this building in Arizona has very little architectural or landscape shading to block solar heat gain.
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Wrong – This multi family building appears to be done in traditional southwest architecture but the lack of useful overhangs, dark colored walls, and lack of tinting on windows will result in significant solar heat gain.
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Wrong: Single sided ventilation without at least two windows, wing walls, and predictable wind directions is ineffective for generating wind-driven crossflow.