Net Zero Housing
What is a Net Zero House?
Simply, a net zero house is a home that is designed to produce all of the energy it uses. This means that special equipment on site, such as solar (photovoltaic) panels or small-scale wind turbines, will actively generate enough electricity on site to power the house. This will cover the energy used for heating and cooling the home, creating hot water for the occupants to use, providing lighting and operating all of the appliances and other equipment in the home. In this way, Net Zero houses offer the ultimate in sustainable building goals; in the long term, they have zero carbon footprint in an operational sense. Coupled with other features, such as greywater recycling and rainwater harvesting, the overall environmental impact of one’s home life could be reduced almost to zero.
How does a Net Zero house “work” differently than a normal house?
Net Zero houses are typically connected to the electrical grid. In this way, they are able to draw power from the grid as any normal house, and send power out to the grid when the home’s energy-producing equipment is creating more electricity than the home can use. In this arrangement, there is no functional difference to how the house operates compared with any conventional building. However, if the power goes out in the grid, the home loses power as well.
Some Net Zero houses may not be connected to an electrical grid. In this situation, the surplus electricity produced on site is temporarily stored in order to be used at a later time. Practically speaking, this means that one does not have access to an unlimited supply of energy at any given point (such as one has if connected to the grid). Monitoring energy consumption in conjunction with data regarding the available energy remaining in storage allows occupants to ensure that they do not run out of energy unexpectedly. However, being isolated from the grid means that even during a grid power failure, these Net Zero homes will still have electricity as they normally would.
Can any house be turned into a Net Zero house?
Technically, yes. As long as the energy used by the home and its occupants over the course of a year is offset by the renewable production of an equal amount of energy in that same calender year, then any home could become Net Zero. However, because of the remaining high cost of renewable energy producing equipment, it makes a great deal more sense to conserve energy first. Because of this economic interplay, most Net Zero houses will very much resemble something in between a “Pretty Good House” and a Passive House in terms of how thermally optimized their envelope is. From a simple perspective, if you reduce your energy usage by half, then you only have to by half as much equipment to produce said energy. As photovoltaic panels in particular come down in price from year to year, this cost-optimization point shifts, but at this point in time, conservation is still the low-hanging fruit. Extra insulation, high-quality windows and doors and sensibly designed buildings still provide exceptional comfort and they almost never need repair or servicing, so they still make excellent sense to employ rather than just adding more solar panels to one’s roof.