A comprehensive energy audit can identify the most cost-effective improvements to congregational buildings and the energy-consuming equipment they contain. The Interfaith Coalition on Energy, an organization dedicated to working with congregations to reduce the costs of operating their facilities, provides energy audits to congregations. Other organizations familiar with the unique characteristics and energy requirements of congregational buildings are The Regeneration Project of California and its affiliate state-based Interfaith Power & Light organizations.
Commissioning is a process in which engineers check and tune up building systems to ensure that they are operating appropriately and efficiently. If possible, choose engineers with expertise in commissioning congregational buildings. Studies have shown that continuously monitoring a building's energy systems can lead to reductions of 10% to 15% in annual energy bills. Savings typically come from resetting existing controls to reduce HVAC waste while maintaining or even increasing comfort levels for occupants. Commissioning usually costs between 5 and 40 cents per square foot.
Upgrade to more-efficient lighting. Compact fluorescent lamps (CFLs) can replace incandescent lamps in many applications, reducing energy use by two-thirds and yielding savings of up to $20 per lamp per year. Also consider "task-ambient lighting," that is, reducing ambient lighting for a general area and focusing light on tasks in work spaces.
Fluorescent lamps. If your building uses T12 fluorescent lamps, relamping with modern T8 lamps and electronic ballasts can reduce your lighting energy consumption by as much as 35%. Adding specular reflectors, new lenses, and occupancy sensors or timers can double the savings. Paybacks of one to three years are common.
LED lights. Use light-emitting diodes (LEDs) for exit and other signs in your building. LED exit signs can last 15 years. LED holiday lights are also now available in a variety of colors and designs from retailers. LEDs use far less energy, last multiple times longer than other light sources, and are more durable.
Daylighting. Take advantage of daylighting where possible to reduce the need for electric light—proper design is critical to avoid glare and overheating. Light shelves, installed high on the inside or outside of a window, will shade and prevent glare in the bottom six feet of a floor, which is where most staff work. The shelves also reflect daylight up onto the ceiling, which indirectly illuminates a room (Figure 3).
Figure 3: Increase daylighting with light shelves
Light shelves reduce glare and reflect sunlight onto the ceiling, distributing daylight further into the building.
Daylighting sensors. Install light sensors—a type of daylighting controls—in offices, bathrooms, kitchens, and worship areas to turn on lights in the space only when daylight is insufficient.
Occupancy sensors. Install occupancy sensors in bathrooms, utility closets, and other less-used spaces to control lighting in response to movement. Occupancy sensors may also be suitable for other building spaces such as staff offices. In addition, occupancy sensors can be used to control plug loads. Plug load sensors range from devices that control a single electrical outlet or piece of equipment to devices that control multiple outlets or a power strip, and they can work together with other sensors. Built-in occupancy sensors can shut off plugged-in devices like printers, monitors, and copiers when nobody is present.
Smart lighting design in parking lots. In its Lighting Handbook, the Illuminating Engineering Society of North America recommends that parking lots be lit at an average of 1 foot-candle or less of light, but most parking lots are designed with far more lighting than that. Using lower-wattage bulbs can actually increase the safety of your lot: An overlit lot can be dangerous to drivers if their eyes cannot adjust quickly enough in the transition from highly lit to dark areas. When designing lighting for a new parking lot, consider using low-wattage metal halide lamps instead of high-pressure sodium lamps in fixtures that direct the light downward. Even with a lower wattage, a congregation could safely use fewer lamps if this choice is made. Metal halide is less efficient than high-pressure sodium in conventional terms, but it puts out more light in the blue part of the spectrum, which turns out to be easier for our eyes to see under low-light conditions.
Photocells and timers. Install lighting controls such as photocells or timers on outdoor lighting. A photocell control will turn on a light at dusk and turn the light off when the photocell detects daylight.
High-efficiency HVAC units. A highly efficient packaged air-conditioning/heating unit can reduce cooling energy consumption by 10% or more over a standard-efficiency, commercial packaged unit. Select equipment that has multiple levels of capacity (compressor stages) with good part-load efficiency. Be careful not to oversize your HVAC system if not all spaces in the building are used, or if there is an imbalance in the amount of use spaces get. If your existing system is old enough, it may be cost-effective to replace it with a new one immediately. A qualified energy auditor, preferably one who is familiar with congregational buildings, can determine which measures are most cost-effective for your building.
Zoned HVAC. In HVAC, a zone consists of a number of rooms that have a similar function and experience similar heating and cooling needs. Consider a separate HVAC system for more frequently used zones in the building that have a similar function and need, such as staff offices.
Demand-controlled ventilation. For spaces that have large swings in occupancy, congregations can save energy by decreasing the amount of outdoor ventilation air supplied by the HVAC system during low-occupancy hours. A demand-controlled ventilation (DCV) system senses the level of carbon dioxide in the return air stream; using that as an indicator of occupancy, the system decreases the amount of outdoor air supplied to the space when carbon dioxide levels are low. DCV systems are particularly applicable to variable-occupancy spaces like worship spaces, meeting rooms, and cafeterias.
Air-to-air heat exchangers. Consider air-to-air energy recovery heat exchangers for your building's ventilation system. These heat exchangers are cost-effective in spaces that are occupied every day, such as staff offices; they reduce the energy needed to cool and heat ventilation makeup air. They are best used in tightly constructed buildings, where they can have a payback period ranging from less than one year up to three years.
Insulation, secondary glazings, and weather-stripping. Consider insulation, secondary glazings, and weather-stripping after the quick fixes of turning things down and off and tuning your HVAC equipment. Older congregational buildings are notoriously energy inefficient because they leak. Insulation, secondary glazings, and weather-stripping hold heat, and they are more cost-effective for older buildings that are continually occupied (and must continually hold heat). If your congregation's buildings leak but are used intermittently, such as a small church used only for Sunday services, these measures may not be cost-effective. A qualified energy auditor, preferably one familiar with congregational buildings, can determine which of these measures are cost-effective for your building.
Entries. During times of high occupancy, entryways allow heating and cooling to escape your building. To reduce losses, construct an interior divider, separating the entryway from the worship area of the building.
Windows. Replacing windows is expensive. In cold climates, your congregation may find it cost-effective to replace old, single-pane windows with more energy-efficient (low-emissivity) windows. If not, an alternative is window film, which typically costs between $1.35 and $3.00/ft2 to install. Window film generally has a lifetime of 7 to 12 years, but it must be installed properly to avoid bubbles, cracks, or damage to your windows. Window film is not appropriate for stained-glass windows because they are uneven. For stained-glass windows, protective glazing such as laminated glass or polycarbonate will decrease drafts, but without proper ventilation and proper glazing may cause damage to the stained glass. On plain-glass windows, use window treatments like drapes and shades and, on walls of south-facing windows, awnings or window film to block solar heat gain in the summer and reduce air conditioning.
Cool roofs. These are not suitable for all congregations, but if your roof needs recoating or painting, consider a cool roof— one that is white or some other highly reflective color—to minimize the amount of heat the building absorbs. This change can often reduce peak cooling demand by 15% to 20%.
Landscaping. Deciduous trees, planted on the west- and south-facing sides of your building, will shade windows, reducing solar gain and therefore air conditioning needs during the summer months.
Appliances and equipment
Purchases. When replacing appliances such as freezers, refrigerators, dishwashers, room air conditioners, water heaters, furnaces, boilers, and even ice makers and washing machines, select energy-efficient models. Also select energy-efficient computers and office equipment. Look for the blue-and-white Energy Star label on many appliances and compare their energy usage to other models. The Energy Star web site has a listing of appliances and products that have earned the Energy Star label. For computers, also look for the 80 PLUS label, which indicates that the computer has an energy-efficient power supply. Visit the 80 PLUS web site for a list of suppliers.
Maintenance. Disconnect unused equipment like refrigerators, freezers, and water heaters, and keep the appliances you do use in good condition. A refrigerator, for example, operates more efficiently when door seals are tight, condenser coils are clean, frost is removed, and airflow for exhaust heat is allowed sufficient clearance.
Water use and water heating
In addition to insulating hot water pipes and fixing leaks, consider installing sink and shower controllers that automatically shut off after a certain length of time. Low-flow faucets and showerheads can also help conserve energy used to heat hot water.
Explore new ways to heat and cool
If you are planning a comprehensive renovation of your heating and cooling system, consider some energy-efficient alternatives:
Geothermal heat pumps. Also known as ground-source heat pumps, these systems rely on the thermal stability of the ground to heat and cool a building. Because the ground temperature below the frost line remains relatively constant throughout the year, it can be used as a heat source in the winter and a heat sink in the summer. The first costs of a geothermal heat pump can be slightly higher than those of other systems, but the life-cycle costs are often lower. The energy consumption of geothermal heat pumps can be 25% to 50% less than that of traditional heating and cooling systems.
Evaporative cooling. An evaporative cooling system uses the natural cooling of evaporation—a tactic that is especially effective in warm, dry climates. It typically uses less than 25% of the energy of a vapor-compression air-conditioning system. First costs may be higher than for a vapor-compression system, but paybacks can be rapid: six months to five years, depending on climate.