The Math and Science of Renewable Energy and Solar Power
Created as an educational learning tool, here Scott Simpson Design + Build explores how to structure and calculate construction elements so that a house can make its own renewable energy off the grid.
What makes this house green is we’re trying to be as efficient with energy as we possibly can. One way is through solar panels for providing heat and electricity to the house. As the sun travels over the horizon it heats up solar panels on the roof which are filled with a fluid which – once it reaches 180 degrees – then circulates through the panels and into the floor of the home to actually heat up the whole house. We use the same solar panels in conjunction with heating the domestic hot water for hot showers and the like. Photovoltaic cells – also solar panels on the roof use the sun to make electricity to power the lights, appliances, garage door, refrigerators, etc. We’re also planning on putting wind turbines on this house to collect the energy from the wind right here by Lake Michigan.
We figure out how much energy we need a few different ways. To make sure that there’s enough energy to heat the house during the wintertime and cool the house in the summertime we do a load calculation which figures out how much heat loss we have per room based on how many windows there are, how much insulation is there in the walls and roof structure. For example, if each room loses 300 BTUs an hour we can figure out how big the furnace needs to be downstairs in order to keep the room temperature at 68 degrees, even when the outdoor temperature may be minus 10. Then we figure out how many amps of electricity each appliance needs and knowing which we’re going to use continuously so we can figure out what size the electric service needs to be – whether it’s 200 amps or 300 amps. The other calculation we would make is for domestic hot water. Shower heads may give off 2.5 gallons of hot water per minute so we figure out how many shower heads will be used and how many occupants there are and then we can figure out how big of a hot water heater we’ll need. For a big family you might need a 100 gallons of hot water in the morning. If you’re a small family, likely only 50 gallons. Solar energy is also used to heat the domestic hot water so a domestic hot water tank is heated to about 120 degrees we’re able to deliver hot water to sinks and faucets and showers.
We are able to monitor the energy efficiencies as well. The photovoltaic sensor tells us how much energy we’re gaining from the sun on the photovoltaic panels on the roof. The solar hot water tank receives heated fluid from the rooftop solar panels and we’re using it to heat up water that then heats up the building through all the floors in the home. When the sun is not shining we have backup heat through a gas-fired boiler which takes energy from natural gas.
We use math and science and the scientific method to solve problems. We are very interested in finding a way to build a house that does not have to rely on the grid and in this house we actually are very, very close to being off the grid.