You may also choose options such as tints, UV blockers, or thicker films that offer security. Low-e films are also emerging as an energy-saving option. B Manufacturer and product name. D Reference Product column shows what type of glazing works best with the film. F Visible Transmittance VT. It includes the solar heat gain coefficient SHGC and visible transmittance VT of the window film, both numbers between 0 and 1.
The lower the SHGC, the better the film is at blocking heat gain. The higher the VT, the more potential for daylighting. Read more about energy performance ratings. Silver, mirror-like films typically are more effective than the colored, more transparent ones. More recently, there are solar control films that have a more neutral appearance and are effective at blocking near IR solar radiation in the summer.
East- and west-facing windows, because of their greater potential for heat gain, can benefit more from these films. North-facing windows won't benefit from them, and south-facing windows may benefit somewhat, but the benefit could be offset by the reduction of heat from the winter sun. There are also window films that have low-e coatings, which can also be effective in reducing winter heat loss and increasing thermal comfort of occupants.
They also typically are effective at reducing near IR solar radiation. Window films can be professionally applied by a skilled installer or are available for do-it-yourself projects at home improvement stores. Window films require extra care for cleaning. If they are primarily absorbing solar radiation tinted films , they can damage insulated glazing unit IGU seals. Most window manufacturers will void their warranties if the film is installed on an IGU. Read more about window films at the Efficient Window Coverings Collaborative.
Exterior shutters and shades are usually made of a variety of materials, including fabric, wood, steel, aluminum, or vinyl. They are most effective at reducing solar heat gain. Shades are typically fabric or vinyl and the material may have openings that allow some visibility through the window.
The larger the openings, the less protection from solar gain. They are usually manually operated, though some can be opened or closed with a crank inside the home. Roller shutters are usually mounted above the window and side channels guide them as they're lowered and raised. When you lower these blinds completely, their slats meet and provide shade, privacy, security, and protection from storms. If partially raised, the blinds allow some air and daylight to enter through windows.
Most exterior shutter systems include a mechanical crank, rod, or motor to allow operation from indoors. National Historic Landmarks, designated for their "exceptional significance in American history," or many buildings individually listed in the National Register often warrant Preservation or Restoration. Buildings that contribute to the significance of a historic district but are not individually listed in the National Register more frequently undergo Rehabilitation for a compatible new use.
Physical condition. What is the existing condition, or degree of material integrity, of the building prior to work? Has the original form survived largely intact or has it been altered over time? Are the alterations an important part of the building's history?
Preservation may be appropriate if distinctive materials, features, and spaces are essentially intact and convey the building's historical significance. If the building requires more extensive repair and replacement, or if alterations or additions are necessary for a new use, then Rehabilitation is probably the most appropriate treatment. Proposed use. Its R-value, ability to absorb and diffuse moisture, impediment to air flow, relatively simple installation, and low cost make it a popular choice.
Cellulose insulation from most manufacturers is available in at least two grades that are characterized by the type of fire retardant added to the insulation. Optimum conditions for installing insulation inside the wall cavity occur in buildings where either the exterior materials or interior finishes have been lost, or where the materials are deteriorated beyond repair and total replacement is necessary.
However, wholesale removal of historic materials either on the exterior or interior face of a historic wall to facilitate insulation is not recommended. Even when the exterior materials, such as wood siding, could potentially be reinstalled, this method, no matter how carefully executed, usually results in damage to, and loss of historic materials. Dense-packed cellulose insulation is being blown in through holes drilled in the sheathing.
Once the operation has been completed, the shingles will be reinstalled. Photo: Edward Minch. If the wall cavity is open, the opportunity to properly install batt insulation is available. A tight fit between the insulation and the adjacent building components is critical to the performance of the insulation. Batt insulation must be cut to the exact length of the cavity. A batt that is too short creates air spaces above and beneath the batt, allowing convection.
A batt that is too long will bunch up, creating air pockets. Air pockets and convection currents significantly reduce the thermal performance of insulation. Each wall cavity should be completely filled. Unfaced, friction-fit batt insulation fluffed to fill the entire wall cavity is recommended. Any air gaps between the insulation and the framing or other assembly components must be avoided. Batts should be split around wiring, pipes, ducts and other elements in the wall rather than be pushed or compressed around obstacles.
When adding insulation to the sidewalls, the band joist area between floors in multi-story, platform-framed buildings should be included in the sidewall insulation retrofit.
The R-value of the insulation installed in the band joist area should be at least equal to the R-value of the insulation in the adjacent wall cavities. In balloon-framed buildings, the wall cavity is continuous between floors except where fire stops have been inserted.
The use of spray foam or foamed-in-place insulation would appear to have great potential for application in historic wood-frame buildings due to their ability to flow into wall cavities and around irregular obstacles.
Their high R-value and function as an air barrier make them a tempting choice. However, their use presents several problems. The injected material bonds tightly to historic materials making its removal difficult, especially if it is encased in an existing wall.
The pressure caused by the expansion rate of these foams within a wall can also damage historic material, including breaking the plaster keys or cracking existing plaster finishes.
Insulation Installed on Either Side of the Wall : Batt, rigid foam board, and spray foam insulation are commonly added to the interior face of walls in existing buildings by furring-out the walls to accommodate the additional thickness. However, this often requires the destruction or alteration of important architectural features, such as cornices, base boards, and window trim, and the removal or covering of plaster or other historic wall finishes.
Insulation installed in this manner is only recommended in buildings where interior spaces and features lack architectural distinction or have lost significance due to previous alterations. The walls have been furred out inappropriately around the historic window trim creating an appearance the interior never had historically. Adding rigid foam insulation to the exterior face of wood-frame buildings, while common practice in new construction, is never an appropriate treatment for historic buildings.
Exterior installation of the foam boards requires removal of the existing siding and trim to install one or more layers of polyisocyanurate or polystyrene foam panels. Depending on the amount of insulation added for the particular climate, the wall thickness may be dramatically increased by moving the siding as much as 4 inches out from the sheathing. Even if the historic siding and trim could be removed and reapplied without significant damage, the historic relationship of windows to walls, walls to eaves, and eaves to roof would be altered, which would compromise the architectural integrity and appearance of the historic building.
Solid Masonry Walls : As with frame buildings, installing insulation on the interior walls of a historic masonry structure should be avoided when it would involve covering or removing important architectural features and finishes, or when the added thickness would significantly alter the historic character of the interior. The addition of insulation on solid masonry walls in cold climates results in a decreased drying rate, an increased frequency of freeze-thaw cycles, and prolonged periods of warmer and colder temperatures of the masonry.
These changes can have a direct effect on the durability of materials. The interior face of a brick masonry wall shows damage that resulted from the installation of a vapor retardant foil facing and thermal insulation.
Depending on the type of masonry, exterior masonry walls can absorb a significant amount of water when it rains. Masonry walls dry both toward the exterior and the interior.
When insulation is added to the interior side of a masonry wall, the insulation material reduces the drying rate of the wall toward the interior, causing the wall to stay wet for longer periods of time. Depending on the local climate, this could result in damage to the historic masonry, damage to interior finishes, and deterioration of wood or steel structural components imbedded in the wall. Masonry walls of buildings that are heated during the winter benefit from the transfer of heat from the inside to the outside face of the walls.
This thermal transfer protects the exterior face of the wall by reducing the possibility of water freezing in the outer layers of the wall, particularly in cold and wet climates. The addition of insulation on the interior of the wall not only prolongs the drying rate of the exterior masonry wall, but keeps it colder as well, thereby increasing the potential for damage due to freeze-thaw cycles.
Extreme swings in temperature may also have negative effects on a historic masonry wall. The addition of insulation materials to a historic masonry wall decreases its ability to transfer heat; thus, walls tend to stay warm or cold for longer periods of time.
In addition, walls exposed to prolonged solar radiation during winter months can also be subject to higher swings in surface temperature during the day. Deleterious effects due to stress caused by expansion and contraction of the building assembly components can result. Buildings with masonry materials of higher porosity, such as those built with low-fired brick, or certain soft stones, are particularly susceptible to freeze-thaw cycles and must be carefully evaluated prior to adding insulation.
Inspection of the masonry in areas that are not heated such as parapets, exposed wing walls, or other parts of the building is particularly important. A noticeable difference in the amount of spalling or sanding of the masonry in these areas could predict that the same type of deterioration will occur throughout the building after the walls are insulated. Brick that was fired at lower temperatures was often used on the inside face of the wall or on secondary elevations. Even masonry walls faced with more robust materials such as granite may have brick, rubble, mortar or other less durable materials as backing.
Spray foams are being used for insulation in many masonry buildings. Their ability to be applied over irregular surfaces, provide good air tightness, and continuity at intersections between, walls, ceilings, floors and window perimeters makes them well suited for use in existing buildings. However, the long-term effects of adding either open- or closed-cell foams to insulate historic masonry walls as well as performance of these products have not been adequately documented.
Use of foam insulation in buildings with poor quality masonry or uncontrolled rising damp problems should be avoided.
Periodic monitoring of the condition of insulated masonry walls is strongly recommended regardless of the insulation material added.
Cool roofs include reflective metal roofs, light-colored or white roofs, and fiberglass shingles that have a coating of reflective crystals. Cool roofs are generally not practical in northern climates where buildings benefit from the added heat gain of a dark-colored roof during colder months. Cool and green roofs are appropriate for use on historic buildings only when they are compatible with their architectural character, such as flat roofs with no visibility.
A white-colored roof that is readily visible is not appropriate for historic metal roofs that were traditionally painted a dark color, such as green or iron oxide red. A white reflective roof is most suitable on flat roofed historic buildings. If a historic building has a slate roof, for example, removing the slate to install a metal roof is not a compatible treatment. It is never appropriate to remove a historic roof if the material is in good or repairable condition to install a cool roof.
However, if the roof has previously been changed to an asphalt shingle roof, fiberglass shingles with special reflective granules may be an appropriate replacement. A green roof consists of a thin layer of vegetation planted over a waterproofing system or in trays installed on top of an existing flat or slightly sloped roof.
Green roofs are primarily beneficial in urban contexts to reduce the heat island effect in cities and to control storm water run-off. A green roof also reduces the cooling load of the building and helps cool the surrounding urban environment, filters air, collects and filters storm water, and can provide urban amenities, including vegetable gardens, for building occupants.
The impact of increased structural loads, added moisture, and potential for leaks must be considered before installing a green roof. A green roof is compatible on a historic building only if the plantings are not visible above the roofline as seen from below. The issue of moisture in insulated assemblies is the subject of much debate. While there is no conclusive way to predict all moisture problems, especially in historic buildings, experts seem to agree on a few basic tenants. Exterior materials in insulated buildings become colder in the winter and stay wet longer following a rain event.
While the wetness may not pose a problem for robust materials, it may speed the deterioration of some building materials, and lead to more frequent maintenance such as repainting of wood or repointing of masonry. Summer moisture problems are most commonly associated with excessive indoor cooling and the use of interior wall finishes that act as vapor retarders paint buildup or vinyl wall coverings.
Good air-sealing at the ceiling plane usually controls moisture in insulated attics. Most problems are caused by poor moisture management, poor detailing which does not allow the building to shed water, or inadequate drainage.
Because of all the uncertainties associated with insulating walls, brick walls in particular, it may be advisable to hire a professional consultant who specializes in the many factors that affect the behavior of moisture in a building and can apply this expertise to the unique characteristics of a particular structure.
Sophisticated tools such as computer modeling are useful to predict the performance of building assemblies, but they require interpretation by a skilled practitioner and the results are only as good as the data entered.
It is important to remember, there are no reliable prescriptive measures to prevent moisture problems. Vapor Retarders Barriers : Vapor retardants are commonly used in modern construction to manage the diffusion of moisture into wall cavities and attics. For vapor retardants to work properly, however, they must be continuous, which makes their installation difficult in existing buildings, and therefore generally not recommended.
Even in new construction, installation of vapor retardants is not always indicated. Formerly, the recommended treatment was to install a vapor retardant toward the heated side of the wall toward the interior space in cold climates and toward the exterior in hot climates. DOE now recommends that if moisture moves both to the interior and exterior of a building for significant parts of the year, it is better not to use a vapor retarder at all.
Devices that utilize solar, geothermal, wind and other sources of energy to help reduce consumption of fossil fuel-generated energy can often be successfully incorporated in historic building retrofits. However, if the alterations or costs required to install these devices do not make their installation economically feasible, buying power generated off site from renewable sources may also be a good alternative. The use of most alternative energy strategies should be pursued only after all other upgrades have been implemented to make the building more energy efficient because their initial installation cost is usually high.
Solar collectors installed in a compatible manner on low sloping sawtooth monitors. Solar Energy: Man has sought to harness the power of solar energy to heat, cool, and illuminate buildings throughout history. Compatible additions to historic buildings also offer opportunities to incorporate passive solar features. Active solar devices, such as solar heat collectors and photovoltaic systems, can be added to historic buildings to decrease reliance on grid-source fossil-fuel powered electricity.
Incorporating active solar devices in existing buildings is becoming more common as solar collector technology advances. Adding this technology to historic buildings, however, must be done in a manner that has a minimal impact on historic roofing materials and preserves their character by placing them in locations with limited or no visibility, i.
Solar collectors used to heat water can be relatively simple. More complex solar collectors heat a fluid or air that is then pumped through the system to heat or cool interior spaces. Photovoltaic panels PV transform solar radiation into electricity. The greatest potential for the use of PV panels in historic buildings is on buildings with large flat roofs, high parapets, or roof configurations that allow solar panels to be installed without being prominently visible.
The feasibility of installing solar devices in small commercial and residential buildings will depend on installation costs, conventional energy rates, and available incentives, all of which will vary with time and location.
The most common systems that utilize this form of energy are geothermal heat pumps, also known as geo-exchange, earth-coupled, ground-source, or water-source heat pumps. Introduced in the late s, geothermal heat pumps rely on heat from the constant temperature of the earth, unlike most other heat pumps which use the outside air temperature as the exchange medium. This makes geothermal heat pumps more efficient than conventional heat pumps because they do not require an electric back-up heat source during prolonged periods of cold weather.
There are many reasons that geothermal heat pumps are well suited for use in historic buildings. They can reduce the amount of energy consumption and emissions considerably, compared to the air exchange systems or electric resistance heating of conventional HVAC systems. They require less equipment space, have fewer moving parts, provide better zone space conditioning, and maintain better internal humidity levels.
Geothermal heat pumps are also quieter because they do not require external air compressors. These include replacing incandescent light bulbs with compact fluorescent bulbs, adjusting thermostats, curing water leaks, replacing high flow shower heads, adding window treatments, and planting shade trees.
Other "big ticket" work items may or may not be worthwhile for your building. Some improvements are worth the investment and provide a quick payback while others can take 10 years or more to recover initial costs.
Larger work items can include duct sealing, installation of an energy efficient heat pump or air conditioner, addition of insulation, duct sealing, installation of energy efficient water heaters and appliances, and retrofits or replacement of windows. Energy rebates are available for some of these improvements through energy providers.
What about historic windows?
0コメント