One of the goals of Solar Decathlon is to showcase the livability of a solar-powered home and prove that one can live without giving up any of the comforts currently enjoyed. In order to achieve this, we turned to a wide array of technology to make our house a functional home.
The most important system, and the basis for the competition, is how to harness energy from the sun. To accomplish this we outfitted our house a roof-mounted 6.88 kW array of high-efficiency Sunpower 215 photovoltaic (PV) panels, also known simply as solar panels. With these panels we are able to generate electricity which (during the competition) will be stored in a large battery bank. From these batteries we will be able to draw all of the necessary power to run all of our appliances, lights and other electricity needs. The residual power will be used to charge our electric Gem car, provided by Solar Decathlon, freeing us from dependence on fossil fuels. Our second means of harnessing solar energy is accomplished by Solar Thermal Collectors. This system absorbs heat from the sun which is transferred into a water supply to provide domestic hot water for uses like showering, dishwashing and laundry.
Both heating and cooling are set up in zones. Each Pod has its own, individually controlled AC and Radiant Floor Heating system. By avoiding one central setting for the entire house, one can heat or cool rooms that are being occupied, thereby saving energy that would normally be used on unoccupied spaces. In addition to this, Radiant Floor systems are generally more efficient and comfortable to the inhabitant than radiators or forced-air systems. Our Radiant Floor system pumps hot water through piping imbedded within the floor. The heat than radiates through the floor and up into the space. As hot air naturally rises, it creates a comfortable circulation of air within the space. For cooling, we have installed individual units for each Pod. Although these are generally oversized for our house’s current volume, they allow for future expansion, without the need to replace or add additional AC units.
Perhaps more important than the method of heating or cooling is how one maintains the desired temperature. To do this, we first turned to the insulation around the house. Properly insulating any building is the most effective way to lower energy bills for heating or cooling. The insulation used on our house was Centria Versawall™ which, along with being completely recyclable and composed of low-emitting materials, are highly efficient. Our 4-inch thick panels have an insulation value of over R-30. In order to achieve this level of insulation with the standard fiberglass you would need to have walls between 9 and 13 inches thick. Other systems in the house help to improve its efficiency with heating and cooling. To maintain proper ventilation, an energy Recovery Ventilator has been installed. This system uses out-going air to pre-heat (in winter) or pre-cool (in summer) the in-coming air, thus lowering the amount of energy needed to bring this fresh air to the desired interior temperature.
It is one thing to be able to produce energy, but quite another to manage it. What would be worse than running out of electricity in the middle of your day? In order to manage our usage of energy, we have equipped the house with energy-efficient products. Many of our appliances are “Energy Star”-rated, meaning that they meet efficiency guidelines set by the US Department of Energy and the EPA. Our refrigerator, dishwasher, clothes washer and dryer are all Energy Star appliances. The most efficient of all is the drawer dishwasher, which is a full 97% more efficient than the typical stand-up version. Many of the lighting fixtures are also very efficient. The general lighting within the house is fluorescent, with some halogen track fixtures as supplementary lighting. We have also employed both white LED fixtures for our exterior lighting as well as some red/green/blue (RGB) color-mixing fixtures that will allow us to paint the upper portion of the Core with colored light.