The Net Zero Energy Home
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In order to reach the goal of near-zero energy, PV panels must be used to offset some of the home’s electricity consumption. But because PV systems are expensive, it is imperative to first build a super-energy-efficient home.
This reduces the amount of electricity needed, which in turn makes it possible to install a smaller PV system. Near Zero Energy Homes incorporate super-energy-efficient building features and a properly sized PV system. Some of those super efficient features are described below.
Typical Features List and Descriptions for CA and NV
- Increased ceiling and wall insulation
- Radiant barrier
- Low air infiltration rate
- High-performance windows
- Engineered HVAC
- Tight duct installation
- Tankless water heater
- All-fluorescent lighting
- Photovoltaic (PV) solar-electric system
Increased ceiling and wall insulation
Increased insulation levels (i.e. R-38 or even R-49) help keep heat out of the house during the summer and maintain heat inside the house during the winter.
Installed on the inside of the roof to reduce solar heat gain and keep the attic cool, radiant barriers are important in California,
where heating and cooling ducts typically run through the attic.
Low air infiltration rate
Tight building envelopes help to reduce air flow into and out of the home. With lower infiltration of unconditioned
air and exfiltration of conditioned air, less conditioning is required, making the home more efficient. Homes with
low air infiltration and exfiltration are often quieter and cleaner.
High-performance glazing increases the comfort of the home and reduces summer cooling requirements by reducing solar heat gain into the home. Spectrally selective glass lets in most of the visible sunlight while blocking approximately 80% of the infrared and ultraviolet solar energy that drives up cooling costs and degrades curtains, carpets, and furniture. In the winter, this glass helps to reduce heating costs by reflecting room-side radiant heat back into the room.
Licensed mechanical engineers size and select HVAC systems based on ACCA Manual J, S, and D. The final product is a properly designed HVAC system with correct duct sizes and registers placed to ensure that conditioned air will be evenly distributed throughout the whole house. These systems improve both energy efficiency and comfort.
Tight duct installation
Tight installation eliminates excessive air leakage in the duct system. Excessive
air leakage makes the HVAC system work harder, using more time and energy to cool and heat the home.
Duct leakage can also increase indoor moisture levels and air flow in and out of the house. It can also make
the house drafty and uncomfortable to live in.
Tankless water heater
Tankless water heaters typically have high efficiencies, with energy factors, or EFs,
of 0.80 or higher. These heaters have no storage tank; the water is heated on demand, which avoids the energy
losses associated with reheating the water that is sitting in storage.
A fluorescent light bulb uses about 75% less energy and lasts up to 10 times longer than an incandescent bulb.
Properly specified fluorescent produce high-quality, efficient lighting.
Photovoltaic (PV) solar-electric system
A PV system generates electricity when the sun shines on the PV panels. The size of the PV system depends on the location, efficiency, and size of the home.