An energy efficient building reduces maintenance and utility costs, but, in many cases, improves durability, lessens noise, increases comfort and creates a healthy and safe indoor environment. A further goal of energy efficient construction is to limit damage to the ecosystem and reduce the use of natural resources like energy, land, water, and raw materials. Reducing energy consumption is crucial because it means fewer emissions of greenhouse gases, a known cause of global warming1. Energy efficient measures can be integrated into new construction or retrofitted into an existing building. Fortunately, there are many methods, materials, and resources to help designers, architects, contractors and building owners move towards creating an energy efficient and high-performance building.
Energy Efficient Techniques in New Construction
New construction gives architects, contractors and building owners the opportunity to design and build an energy efficient building, and even a net-zero energy project. A net-zero energy building consumes less than or equal to the amount of energy that it produces on site through renewable resources. The steps for constructing a modern energy efficient structure begin with choosing a site and implementing a detailed, holistic design plan.
Site Selection and Placement of an Energy Efficient Building
1. Ensure that public transportation is available and local shopping is nearby. Limiting travel time and the use of private transportation will reduce wear and tear on vehicles and save gas.
2. Build near existing infrastructure to save money and resources.
Design of an Energy Efficient Building
3. Implementing a whole-building systems approach to new construction is the most efficient way to achieve an energy efficient building. The whole-building approach treats the building as one energy system with separate, but dependent parts. Each part affects the performance of the entire system (the whole-building).
4. The design should make efficient use of water and electricity and other natural resources and energy sources.
5. To minimize waste and materials, choose the smallest possible building for the intended application.
6. The design should strive to meet the Energy Star requirements for sustainability, the Leadership in Energy and Environmental Design (LEED) standards, and the International Green Construction Code (IgCC).
7.The design of an energy efficient building should easily allow for future retrofits without impacting the performance of the building.
8. The design should take into consideration building orientation. The way a structure is situated on a site and the placement of windows, rooflines and other features is critical for efficiency.
9. The design of an energy efficient building should be sustainable. A sustainable design aims to lessen depletion of critical resources like land, water, energy, and raw materials. Sustainable design of facilities and infrastructure also averts the destruction of the ecosystem.
10. Utilizing an energy modeling software is an effective way to estimate a building's energy use. The model's output can help architects, contractors, and building owners modify a building performance and cost before construction starts.
Wall Assembly of an Energy Efficient Building
11. A continuous layer of insulation (CI) around the building envelope is essential to an energy efficient building. Continuous insulation increases the effective R-value of the structure, eliminates condensation, and creates a comfortable space for the building’s occupants. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE 90.1) and the International Energy Conservation Code (2015 IECC) also require continuous insulation in most applications.
12. For wood-framed construction, provide more space for insulation between interior and exterior walls by utilizing 2X6 studs instead of 2X4 studs.
13. For wood-framed construction, use a high-quality insulation like spray foam insulation. Spray foam insulation can provide an air barrier and is a far superior insulation method over a less expensive insulation material like batts and blankets.
14. Because tightly sealed, energy-efficient, wood-frame buildings are vulnerable to moisture accumulation in the wall cavities, the exterior of the building must be wrapped in a water-resistant and breathable material. Moisture in a building's walls is serious because moisture can lead to wood rot (caused by fungi) and expensive repairs. Moisture may also cause the growth of mold, which is unhealthy to the occupants of the structure. It is essential that a wood-frame building envelope controls moisture entry, accumulation, and removal.
15. An energy efficient wood-framed building utilizes advanced house framing (also known as optimum value engineering). Advanced house framing reduces lumber use and waste and improves the energy efficiency of a wood-framed house.
16. Structural insulated panel (SIP) can save up to 50 percent in energy costs. SIPs are made from a layer of foam insulation placed between pieces of plywood, strand board or cement panels.
17. To create an energy efficient concrete structure, utilize concrete wall systems with integral insulation made of expanded polystyrene insulation (EPS) or other insulating foam. Insulated concrete forms and insulated concrete blocks form a layer of continuous insulation, substantially eliminating thermal bridging through the wall.
18. For concrete construction, apply an air and moisture barrier to the exterior face of the concrete wall. Fully adhered membranes and fluid applied air and moisture barriers work well with concrete construction. Air tightness of a building has a significant positive impact to overall energy efficiency.
An Energy Efficient Roof
An energy efficient roof (cool roof) is designed to reflect sunlight and absorb less heat than a standard roof. Cool roofs reduce energy bills, improve indoor comfort, and may extend the service life of the roof. There are several techniques for creating a cool roof.
19. Cool roof coatings have special reflective pigments or are white to reflect sunlight. A light-colored roof absorbs less than 50 percent of the solar energy, which reduces a roof’s temperature. In contrast, dark roofs absorb 90 percent of the solar energy.
20. Selecting a cool roof is dependent on the slope of a roof. For low-sloped roofs, with a pitch of 9.5 degrees or less, choose single-ply membranes that are light-colored and reflect the sun. Single-ply membranes are pre-fabricated sheets that are rolled onto the roof and connected with mechanical fasteners, bonded with chemical adhesives, or kept in place with ballast (stones, gravel or pavers).
21. Painted metal roofs also satisfy low-slope cool roof requirements for solar reflectance.
22. For steep sloped cool roofs, choose shingles. Cool shingle roofs are overlapping panels made from wood, asphalt, metals, or polymers. The solar reflective granules that coat the shingles keep the roof cool.
23.For steep sloped cool roofs, tiles, made from concrete, clay or slate, are also a good choice. Most tiles are naturally reflective; however, treatments are available for tiles that are not naturally reflective.
24. Green roofs are perfect for urban buildings with flat or shallow-pit roofs. Green roofs include anything from basic plant cover to a working garden.
Glazing Systems (windows, skylights, vents, and glass portions of doors) of an Energy Efficient Building
25. Purchase energy efficient windows appropriate for your climate zone.
26. Installing storm windows can lower energy bills by up to $350 a year.
27. In the northern hemisphere, face major glazing areas south to take advantage of the solar heat gain in winter months when the sun is low.
28. For warmer climates, limit south facing glazing and install overhangs or other shading devices over the south facing windows to prevent excessive heat gain during the summer.
29. In the southern hemisphere, north-facing windows are best.
30. Low-emissivity (low-e) window glazing helps to control solar heat loss and gains. In fact, computer simulations indicate that advanced window glazing reduces the space cooling requirements of new homes in warm climates by more than 40 percent.
31. Choose energy-efficient skylights that have established minimum ENERGY STAR® performance rating criteria by climate.
32. New exterior doors typically fit and insulate better than old doors. When selecting a new door, consider buying the most energy-efficient door possible according to energy performance ratings associated with the local climate and the building's design.
33. If you plan to keep an existing exterior door, a storm door is a good investment.
34. Improve an existing window’s energy efficiency with caulking and weather-stripping, and the use of thermal window treatments or coverings.
Ventilation in an Energy-Efficient Building
Proper ventilation is necessary for an energy-efficient home because air sealing techniques may trap pollutants (like formaldehyde, volatile organic compounds, and radon). Ventilation also helps control moisture, which can cause mold growth and structural damage.
35. An energy efficient building should include an energy recovery ventilation system. An energy recovery ventilation system provides controlled ventilation and minimizes energy loss by transferring energy from conditioned air going out to fresh incoming air.
36. Install localized exhaust fans above kitchen ranges and in bathrooms to create spot ventilation. Spot ventilation improves the effectiveness of natural and whole-house ventilation by removing indoor air pollution and moisture.
37. While natural ventilation is the least expensive and most energy-efficient way to cool buildings, it works best when combined with spot ventilation, ceiling fans, and window fans. For large homes and buildings, whole buildings fans are a worthwhile investment.
Heating and Cooling Systems of an Energy Efficient Building
Cooling, heating, and water heating account for the largest energy expenses in homes and commercial buildings. Incorporating energy efficient measures into a building's heating and cooling systems are essential to creating an energy-efficient structure.
38. Choose a high energy efficient heating, ventilation and air conditioning (HVAC) system. For instance, the most efficient HVAC system is 95 percent efficient; meaning 5 percent of the energy produced is expelled. Consider replacing the HVAC every ten years.
39. Proper installation of a new HVAC system is essential to an energy efficient building. Improperly installed HVAC systems can reduce a system's efficiency by up to 30 percent.
40. Ensure that the fronts of vents are clear of obstructions like furniture and paper. Blocked vents require as much as 25 percent more energy to distribute air.
41. Install a programmable thermostat to manage periods of time where the heating and cooling can be turned down and up.
42. Change the air filter of the HVAC system as prescribed by the equipment manufacturer. Dirty filters slow down air flow and make the system work harder to keep a building warm or cool. Also, a clean filter prevents dust and dirt from building up in the system. Dust and dirt in an HVAC can lead to expensive maintenance and early system failure.
43. Maintain the HVAC annually to ensure its high efficiency, longevity, and the comfort level of the building.
44. To maintain an energy efficient building sealing the ducts that move air to-and-from the HVAC system is crucial. It is of particular importance to seal the ducts that run through the attic, crawlspace, unheated basement, or garage. Seal the seams and connections of ducts with sealant (mastic) or metal-backed (foil) tape then wrap the ducts in insulation. The insulation will keep the ducts from getting cold in the winter and hot in the summer.
High-Efficiency Water Heaters
Because heating water accounts for about 7 percent of commercial building energy use and 15 percent of home energy use, it is essential, for a high-efficiency building, to consider energy efficiency when selecting a water heating system.
45. A tankless water heater heats water just when needed, eliminating energy lost during the standby operation.
47. A high-efficiency heat pump water heater transfers energy from the surrounding air to water in a storage tank. High-efficiency heat pump water heaters are most effective in warm climates with long cooling seasons.
Renewable Energy Sources for an Energy Efficient Building
49. Install grid-tied solar photovoltaic (PV) panels for a cost-effective form of renewable energy. Solar photovoltaic can power all the energy needs of a building including lighting, heating and cooling systems, appliances and hot water.
50. Install a small wind system either connected to the electric grid through your power provider or stand-alone (off-grid). A small wind electric system can lower electric bill by 50 to 90 percent. A variety of applications can use a small wind system, including water pumps.
51. A small “hybrid” electric system combines home wind electric and home solar electric (photovoltaic or PV) technologies. A hybrid system is best in regions where peak times for wind and solar systems occur at different periods of the day and year.
52. On properties with flowing water, Microhydropower is a simple and consistent form of renewable energy. A microhydropower system requires a turbine, water wheel, and pump to transform the energy of flowing water into rotational energy, and then into electricity.
Energy Efficient Lighting
53. Switch to light-emitting diode (LED) light bulbs. LED bulbs are energy-efficient, durable, and long-lasting.
54. Install controls such as timers and photocells that turn lights off when not in use. Dimmers, when used to lower light levels, also save money and energy.
55. Use task lighting where suitable. A task light consumes far less energy than a typical overhead lighting fixture.
Energy Efficient Appliances
56. Select ENERGY STAR® refrigerators because they use 15 percent less energy than non-qualified models. Also, refrigerators with top-mounted freezers use 10-25 percent less energy than side-by-side or bottom-mount units.
57. Select ENERGY STAR® dishwashers. ENERGY STAR® dishwashers use less water and energy than required by federal standards. Dishwashers are currently required to use 4.25 gallons of water per cycle or less.
59. An automatic electric ignition system on a natural gas oven or range can save gas because the pilot light is not continuously burning.
60. Monitor flame color of natural gas ovens or ranges. A yellow flame indicates the gas is not burning efficiently and an adjustment is needed.
61. Keep ENERGY STAR® range-top burners and reflectors clean, so they will reflect the heat better and save energy.
62. Select clothes washers and dryers that have earned the ENERGY STAR® rating.
Energy Efficient Electronics, Computers, and Office Equipment
63. Whether working in an office building or from home, utilizing energy efficient electronics, computers, and office equipment can save building owners energy and money.
64. Purchase ENERGY STAR®-labeled office equipment which can save as much as half the electricity of standard office equipment.
65. Use a laptop computer because laptops use much less energy than desktop computers.
66. Use sleep mode and power management features on the computer.
67. Unplug electronics when not in use because many electronics continue to draw a small amount of power even when switched off. These little draws on energy can occur on most appliances that use electricity: DVD players, TVs, stereos, computers, battery chargers, and kitchen appliances.
68. The U.S. Department of Energy's (DOE) recommends the following guidelines for turning off computers, monitors, printers, etc. to save energy and money.
- Turn off the monitor if not using the computer for more than 20 minutes.
- Turn off both the CPU and monitor if not using the computer for more than 2 hours.
Other Ways to Make a Building More Energy Efficient
69. Incorporate energy efficient landscaping into the overall building design. For instance, shady landscaping protects a building from direct sunlight during the summer and allows more sunlight to reach through windows during the winter. Additionally, planting trees on the southern and western side of a building can keep the building cooler because it blocks sunlight from falling directly on the building during the winter; then, when after the trees lose their leaves, the trees allow more sunlight to reach the building.
70. Optimize system control strategies with occupancy sensors, CO2 sensors, and other air quality alarms.
71. Choose window treatments or coverings not only for decoration but also for saving energy. For example, triple layer cellular shades can significantly reduce your utility bill and make the interior of a building more comfortable.
While the upfront costs of making a building energy efficient may seem high, building owners soon recoup the extra cost through reduced utility and maintenance expenses. Also, incorporating energy efficient features into a building make it more valuable. In fact, a McGraw-Hill Construction survey reported that new green building values were 7 percent greater than new non-green building projects. Green retrofit building values were 5 percent greater than non-green retrofit buildings. Today’s energy efficient technology is extensive and can be incorporated into all sizes and price ranges of new construction and remodel projects.
1Global warming refers to the modern-day rise in global temperature near the earth’s surface. The increase in temperature is due to increasing concentrations of greenhouse gases (carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases) in the atmosphere. The explanation for global warming is straightforward.
The sun’s energy falls on the earth as ultraviolet, visible (light), and infrared (heat) electromagnetic energy. The earth absorbs some of the sun’s energy as thermal energy. The earth reflects another part of the sun’s energy (infrared heat) back into the atmosphere where it either passes through the atmosphere or is reflected back to the earth’s surface. Nitrogen and oxygen, which are the dominant gases in the atmosphere, allow infrared heat to pass through the atmosphere, while the greenhouse gases absorb infrared heat and redirect it back to the earth. The more greenhouse gases, the more heat is redirected back to earth; hence the increase in global temperatures near the earth’s surface.
According to the National Climatic Data Center, before the Industrial Revolution (about the year 1800), levels of carbon dioxide were about 280 parts per million by volume (ppmv); current levels are greater than 380 ppmv and increasing at a rate of 1.9 ppm per year since 2000. The burning of fossil fuels (coal, natural gas, and oil), solid waste, trees and wood products, and certain chemical reactions (e.g., manufacture of cement) are responsible for the increase in greenhouse gases. Furthermore, because plants absorb CO2 (thus remove it from the atmosphere) as part of their biological carbon cycle, deforestation and also lead to increased CO2 levels in the atmosphere. Adverse impacts of global warming are extensive. A few of the impacts include rising sea levels due to increasing rates of glacial melting, more acidic oceans due to increasing carbon dioxide levels, and more frequent and severe weather events – like hurricanes.