Taking a page from the solar decathlon that runs annually in Washington DC, New Town Builders in Denver will complete their first net zero home in the Stapleton neighborhood later this year. As an example of what future homes (and buildings in general) can do, the net zero home will produce as much energy as it consumes. Built in close vicinity to HGTV’s Green Home, which will be given away soon (sorry, the sweepstakes is now closed and no longer accepting entries), New Town’s home will not rely on energy from the grid to power the house. While it will be tied to the grid to feedback extra energy produced and draw from it when the home does not generate energy, the net amount drawn from utilities will be zero.
Scheduled to open in the summer of 2011, the house has the following four goals:
1. To generate as much energy as it uses over the period of a year. This is measured by the Home Energy Rating System, also known as a HERS rating. Homes in Denver’s older neighborhoods typically have HERS scores between 100 and 200. New homes built today based on Denver’s current building code have a HERS rating of 100; thus, a lower rating is better. Energy Star requires a HERS rating of 85. All of New Town’s single family homes achieve HERS ratings in the low to mid 50’s. New Town’s Zero Energy Home will achieve a HERS rating of 0 by building to even higher levels of conservation and generation.
2. To ensure an attractive and comfortable home in which to live. This will demonstrate to the consumer that a Zero Energy Home isn’t some unique one-off design that people would find unattractive. To accomplish this, New Town is using one of its existing plans with a modified exterior wall, so it will live like and look like any other New Town home.
3. To find a cost effective design that can be constructed within the normal processes of a production builder so that New Town may offer this feature to the market on an economically viable basis.
4. To create a home that does not burden the homeowner with complicated, exotic systems that require constant monitoring and maintenance. In fact, the Zero Energy Home may require less maintenance than the average home because of the high standards of construction.
In order to develop this property, New Town Builders received assistance from the National Renewable Energy Lab (NREL) in Golden, CO. NREL recently completed a net zero building on its campus that earned LEED Platinum. The structure was mentioned briefly in a previous post.
In order to achieve the goal of building that produces as much energy as it consumes, there must be changes to the standard structure. Here are some of the extra measures being taken by New Town as they construct their Zero Energy Home:
• A double 2×4 exterior wall with staggered studs and a gap between the exterior 2×4 wall and the interior 2×4 wall.
• The exterior wall will be insulated with one inch of spray foam to seal and insulate the wall. The entire remaining cavity will be filled with blown-in cellulose insulation.
• Additional foundation insulation.
• Spray foam insulation at the seams where the wall meets the roof, foundation, windows and doors.
• More energy efficient widows with decreased U-value.
• Even higher efficiency mechanical systems including a tankless water heater, 96% efficient furnace, 16 SEER or better air conditioning unit, and a continuous whole house energy recovery exhaust fan in lieu of a fresh air ventilator.
• Energy Star appliances including refrigerator.
• 100% CFL and LED lighting, eliminating incandescent lighting.
• Additional photovoltaic panels increasing the kilowatts generated.
These features go beyond New Town’s current practices, but with the economic benefit to the homeowner, they may become standard; if the market is there. Since utility bills are one of the greatest expenses for homeowners (after the mortgage), this is a great incentive for potential home buyers. In fact, according to the company, all of their new homes feature a 3-kilowatt solar panel system, thicker walls, and insulation. Executives at New Town Builders say there are tax credits, subsidies and immediate savings on utility bills, making their homes attractive for buyers.
The most affordable New Town Builders single-family home that comes standard with solar panels and energy-efficient features costs $354,000. Multi-family homes with solar power start at $170,000.