1. A Whole-Building System Approach for Designing a Green Home
The whole-building system approach treats a house as a single energy system in which each part impacts the efficiency of the entire home. The whole-building system approach efficiently uses electricity, water, and other natural resources and strives to reduce material consumption and waste. Also, it ensures that all the building professionals are informed and understand every aspect of the design that impacts energy use in the house. The goal of the whole-building system approach is to create a home with a healthy and safe indoor environment, lower utility and maintenance costs, and improved durability and comfort. Homeowners, architects, and contractors concur that designing a green home needs a whole-building system approach.
2. A Green Home has a High Performance Building Envelope
A high performance building envelope minimizes heat, air and moisture infiltration and is crucial to creating a green home. Essential design components of a high performance building envelope are continuous insulation (CI)4 and application of an air and moisture barrier. Continuous insulation prevents gaps of insulation where heat can enter or escape (thermal bridging), and a high performance air and moisture barrier stops air leakage which degrades energy performance of a building. Moisture resistance is key to preventing rot and the growth of mold and mildew, which can tremendously degrade the integrity and IEQ of a home. A high performance building envelope should also include energy efficient windows, skylights, and doors appropriate to the home’s climate zone. Essential to green home design is a high performance building envelope that minimizes heat, air and moisture infiltration within a home.
3. Cool Roofs of a Green Home
A cool roof keeps the home and attic spaces cool by shielding against solar heat gain. Materials for a cool roof include high thermal mass materials5 like clay, tiles, or slate that are reflective or have light colored pigments that cast back the sunlight. Cool roofs reduce energy bills and improve indoor comfort. Cool roofs can also extend the roof’s service life.
4. The Heating, Cooling and Ventilation Systems of a Green Home
Because a home’s heating and cooling system account for 48 percent of a home’s energy use, the design of a green home should consider high-efficiency heating and cooling systems that use less energy. The most efficient HVAC system is 95 percent efficient; meaning 5 percent of the energy produced is lost. Controlling ventilation of a green home is also critical because the air-tightness of a green home can trap pollutants (like radon, formaldehyde, and volatile organic compounds). Methods of ventilation may include an energy recovery ventilation system and spot ventilation, such as exhaust fans in the bathroom and kitchen, along with natural ventilation.
5. Renewable Energy Sources of an Energy-Efficient Home
The design of a stainable home should strive to generate as much energy as it uses by installing renewable energy measures: for example, microhydropower, solar photovoltaic (PV) panels, wind system, and small “hybrid” electric system. Renewable energy sources can lessen or even eliminate a home’s utility bills and may even have tax incentives.
