hvac systems
What’s the use of an uninhabitable solar-powered house? To enhance the adoption of solar energy as a residential technology, we must be able to keep our home comfortable by maintaining a constant, cozy temperature, high indoor air quality, and pleasant humidity levels. However, according to the U.S. Energy Information Administration, approximately 41 percent of residential energy is used in heating, ventilation, and air conditioning (HVAC), and another 9 percent in water heating. The adoption of efficient HVAC systems is an important step toward reducing residential energy use.
We have created a system that maintains indoor environmental conditions as efficiently as possible by using powerful insulation, solar thermal collectors, and variable-speed equipment to reduce electrical load. Insulation keeps heat from entering or leaving the house, significantly reducing the amount of energy required to maintain temperature levels. Most houses are poorly insulated and extremely prone to air leakage, creating a need for constant heating or cooling. In New York State, the minimum required insulation value is around R-25. We built our house out of structural insulated panels (SIPs), which create a much “tighter” envelope and feature a polyurethane foam core with value R-40; our models indicate a 75 percent decrease in energy usage. Conservation is indeed the first step for sustainability.
Furthermore, it is a simple matter to use the sun’s rays for water heating. Typical homes use boilers to heat water, burning natural gas or wasting electricity with resistance heating. For centuries, people have installed water tanks on their roofs and painted them black to use free heat from the sun to warm their water. Our home uses a new spin on that ancient technology—solar thermal collectors called evacuated tubes. Unlike photovoltaic panels, solar thermal collectors catch the sun’s rays and trap their heat, rather than converting them to electricity. Evacuated tubes are advanced, high-efficiency black tubes that trap heat inside of a vacuum and heat up a pipe of running water. Our models are the Sunda Seido® evacuated tubes, which reach a maximum temperature of 374°F. The solar hot water system is large enough to heat two tanks—one for domestic hot water and one that runs through a hydronic coil in the duct system and heats air, so that for many days of the year we don’t have to use any electricity for heating.
Like many homes in the United States, our solar home features an air-source heat pump that heats and cools the house through a forced-air system. Unlike typical homes, the air handler has variable speeds, the ducts are well sealed, and the heat pump is a backup to a solar hot-water supply. Even the fresh air that comes into the house from outside runs through an Energy Recovery Ventilator (ERV) that transfers heat between incoming and outgoing air, reducing the energy required to keep the house thermally comfortable. It is very possible to reduce the energy required to heat and cool a building, and the wide implementation of these simple measures would significantly reduce global energy use.
HVAC controls are provided by Lonworks-compatible, free-programmable controllers by Distech-Controls, Inc.
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Products:
- Sunda Solar Seido® evacuated tube collectors and mounting kits – Total Retail Cost $6,370 (donated by Sun Spot Solar)
- Silicon Solar solar hot water tanks – Total Retail Cost $3,600 (donated)
- Lennox air handler and heat pump units – Total Retail Cost $3,300 (donated by HSC Associates)
- Distech Controls, Inc. Lonworks-compatible free-programmable controllers – Total Retail Cost $2,875 (donated)
- Viega Pex® piping and Manablock® manifold – Total Retail Cost $1,700 (donated)
- RenewAire energy recovery ventilator – Total Retail Cost $Insert- Morghan/Robert (donated)
- Whirlpool 35 pint dehumidifier – Total Retail Cost - $170
