Building Envelope Tips
Add Roof Insulation
The time to add roof insulation is when you are building or replacing the roof. Whether the project is a 19th century historic property with a lead-coated copper roof or a flat-roofed industrial building from the 1930s, roof replacement is an opportunity to add insulation, including a vapor barrier. This is one of the most cost-effective energy conservation measures available. The cost to increase insulation is a small portion of the overall roofing project and can result in a rapid payback.
Allow elevators to shut down slowly
To conserve energy, allow elevators to timer out and shut down slowly. They should idle long enough so that the power consumption is equal to or just less than power consumed in motor generator starting.
Aluminum Windows Need Thermal Breaks
To improve the thermal-insulating characteristics of aluminum frame windows, specify that the window must include a thermal break-an insulating section placed between the inner and outer aluminum sections of the frames. With a thermal break, aluminum frame thermal conductivity characteristics approach that of wood.
Artificial Lighting and Air Conditioning
Artificial lighting and air conditioning consume the largest amount of electrical energy in a typical commercial building. The two are tied together in that the more artificial lighting used, the greater the heat load imposed on the air conditioning system from lamps and ballasts. Carefully increasing the amount of natural light will decrease the need for artificial light, reducing energy in both lighting and air conditioning systems. However, West facing glass can bring in a significant amount of heat which can be costly to cool in the warmer months. Consider planting trees that lose their leaves in multi-story buildings to shade this glass.
Consider installing new elevators
Newer elevators are more energy efficient than older ones which use motor generators that run constantly. Despite this benefit, energy savings alone do not justify the cost of installing new elevators. New direct drive elevators may still be a good investment because they save on maintenance costs and are environmentally kind.
Control heat flow and light energy
When designing new facilities or renovations, select strategies to control heat flow and light energy to minimize energy costs. Light energy can be controlled using overhangs to shade windows, shading glass surfaces, and using glazing material for exposed window surfaces. Other methods for controlling heat flow include selecting the correct materials for the walls and roof and using natural ventilation and landscaping. Your utility company can help you select those strategies which provide enough savings to justify their expense.
Just enlarging window openings will not correct daylighting problems. Daylighting needs to be distributed relatively evenly, and that becomes more difficult as a building rises several stories. Near the ground level, some daylight bounces off the landscaping and streetscaping to balance the directional light from the sky. But in high-rise buildings, that balance must be accomplished artificially by using reflectors and diffusers often built into the glass.
Fix Air Leaks
Seventy-five percent of a building's total air loss is from small leaks. Seal electrical outlets and gaps between moldings, as well as plumbing and wiring penetrations. Attic checkpoints include hatches, plumbing vents, chimneys and other roof or wall penetrations. Many areas can be sealed with a caulk gun and tubes of silicone or urethane caulking. For larger areas, foam sealants may work best. Outlet plugs and foam pads that are installed behind outlet and switch covers are wise investments.
Incorporate Low-E Glazing
Incorporating low-E glazing will improve the energy efficiency of your facility year-round. During the cooling season, long-wave infrared radiation from outside the facility is blocked before it can pass through the glass, thus reducing the cooling load. During the heating season, long-wave infrared radiation from objects within the facility is reflected back into the conditioned space, thus lowering the heat loss through the glass.
Insulate Brick Walls
Uninsulated brick walls are very common, particularly in buildings constructed prior to 1960. You can realize significant energy savings by adding insulation using one of three methods: furring the interior surface, insulating the cavity, or insulating the exterior. Furring the interior surface is the simplest and least expensive approach, and provides a finished wall surface. Generally, this method entails framing the interior with studs or runners, placing insulation between the runners, and finishing the surface of the wall.
Insulate Uninsulated Brick Walls
Insulate uninsulated brick walls. Uninsulated brick walls are very common, especially in buildings constructed prior to 1960. These walls can be insulated using three methods-furring the interior surface, insulating the cavity or insulating the exterior. Furring the interior surfaces is relatively simple, inexpensive and provides a finished wall surface. Generally, the interior is framed with studs or runners, insulation is placed between the runners, and the surface of the wall is finished.
Interior Window Treatments
In addition to their aesthetic values, interior window treatments can reduce energy consumption. Insulating vertical or horizontal blinds and/or draperies can reduce heat loss and solar gain through window openings.
Keep an Eye Out for Solar Heat Gain
Keep an eye out for solar heat gain. Solar heat gain, particularly in buildings with large areas of south-facing glass, can cause serious problems in maintaining comfort levels. Window tints or reflective coatings are available that will reflect up to 90 percent of the solar heat gain striking the window. The windows can provide energy savings in all but the most northern climates, where solar heat gain can make a significant contribution to reduce the winter heat load in the building. As a rule of thumb, if the walls of a building are more than 25 percent glass, the building can benefit from solar control glass. The further south and t-he higher the percentage of glass, the higher the percentage of solar energy that should be blocked.
Proper landscaping not only increases the attractiveness of a facility, but also decreases energy consumption in smaller, low-rise buildings. Trees, planted near their mature size, provide shade for low, east- or west-facing windows. Both trees and shrubs control glare from neighboring buildings, shade parking lots, reduce the temperature of the pavement, and lower the temperature around a building. Plants control and funnel breezes into ventilated portions of buildings where the direction and speed of the prevailing winds are dependable.
Landscape to Reduce Energy Consumption
In addition to increasing the attractiveness of a building site, landscaping can be put to use to decrease energy consumption in smaller, low-rise buildings. Deciduous trees can be planted to provide shade for low, east- or west-facing windows, although they have to be planted near their mature size in order to achieve a significant effect. Trees and shrubs can control glare from adjacent surfaces and materials such as neighboring buildings and reflecting glass surfaces. They can also shade parking lot surfaces, reducing the temperature of the paving materials and lowering ambient air temperatures around buildings. Finally, plant materials can be used to control and funnel breezes into ventilated portions of buildings where the direction and speed of the prevailing winds are dependable.
New Facilities and Renovation Decisions
New facilities or renovations can be designed to control heat flow and light energy in a way to minimize energy costs. The key is to examine the various strategies for envelope energy conservation and to select those strategies which provide enough savings to justify their expense. These strategies include: incorporating overhangs to shade windows; shading glass surfaces from radiant heat while introducing natural daylight into a building, or selecting the appropriate glazing material for exposed window surfaces; selecting the correct materials for opaque surfaces (walls and roof); and using natural ventilation and landscape materials where appropriate.
Seal outlets and gaps
To prevent 75 percent of a building's total air loss, seal subtle leaks. Seal electrical outlets and gaps between moldings, as well as plumbing and wiring penetrations. In the attic, pay particular attention to hatches, plumbing vents, chimneys, and other roof or wall penetrations. In smaller areas, use a caulk gun and several tubes of silicones or urethane caulking. In larger areas, use foam sealants. Outlet plugs and foam pads installed behind outlet and switch covers are wise investments, particularly in campus-like building complexes in colder climates.
Selecting Replacement Windows
Select replacement windows with a 0.46 U-value or better, with optical properties that are appropriate for building use. (U-0.46 is a low-E window in a thermally improved metal frame.)
Use low-E glazing in windows
To improve the energy efficiency of your facility year-round, use low-E glazing in your windows. During hot weather, this glazing blocks long-wave infrared radiation before it can pass through the glass, thus reducing the need for air conditioning. During cold weather, long-wave infrared radiation from objects within the facility is reflected into the conditioned space, lowering heat loss through the windows.
Wall Color Is Important
Internal walls influence window design and placement. Highly reflective-but not glossy-light-colored walls will spread daylight back from sidewalls. Jewel-toned walls will absorb more light and may require more supplemental lighting sources.
Window Films Cut Cooling Costs
If you can't stand the heat, leave the heat out of the kitchen! A building had many offices with large windows facing south. Even with the shades drawn, the air conditioning could not keep up. The owners considered increasing chiller capacity by 50 percent. Instead, an energy engineer suggested window films. Now the offices are comfortable without the addition of chiller capacity. The electric bills have gone down. And the occupants can leave their shades open to enjoy the view. Window films not only reduce air conditioning loads but also help reduce heating energy use. In optimum situations, energy savings frequently pay back the cost of film installation in a year or less. In a surprisingly large number of cases, building owners have been able to pay back the cost of window film installation directly from energy savings.