Energy efficient houses are growing in popularity across the United States, and with very good reason. They present many significant benefits to the homeowner, including reduced heating and cooling costs. These homes also tend to be more comfortable due to the controlled humidity and temperature, as well as quieter due to the extra insulation.
Houses of any size and style can be made to require relatively low amounts of energy, while remaining comfortable and enjoyable for the homeowners. Although there are many design options available, there are a few key elements that all energy efficient homes share:
- A tightly sealed thermal envelope (i.e. a high R-value)
- Controlled ventilation
- Lower heating and cooling costs
Below, we break down each of these elements of energy efficient houses in greater detail.
1. Tightly Sealed Thermal Envelope
The thermal envelope is one of the most critical components of a low energy house. In simplest terms, the thermal envelope is anything and everything that helps to protect the interior of your home from the outside environment, including energy-efficient windows and insulated doors.
The thermal envelope is essential to minimizing heat transfer (losing necessary heat in cold climates or gaining unwanted heat in warm climates) and water vapor diffusion in your home. Both heat transfer and water vapor diffusion can have negative impacts on the integrity of your home’s structure, as well as the health and comfort of your family.
Homes that have a tightly sealed thermal envelope will always have a high R-value, which is a measure of a material’s resistance to heat traveling through it. The higher the R-value, the more heat resistance there is, making the material more energy efficient.
2. Controlled Ventilation
Because an energy efficient home is tightly sealed, it makes it fairly simple ventilate the building in a controlled way. Controlled ventilation reduces air moisture infiltration, which:
- Minimizes the health risks from indoor air pollutants
- Promotes a more comfortable atmosphere
- Reduces the likelihood of structural damage from excessive moisture accumulation
Heat recovery ventilators (HRV) or energy recovery ventilators (ERV) are growing in use for controlled ventilation in tight homes. These devices salvage about 80% of the energy from the stale exhaust of home appliances (such as water heaters and furnaces), then deliver that energy to the fresh entering air by way of a heat exchanger inside the device.
Other ventilation devices such as through-the-wall and “trickle” vents may be used in conjunction with an exhaust fan. However, they are more expensive to operate and have no energy recovery features to precondition the incoming air. This sort of ventilation strategy is recommended only for very mild to low humidity climates.
3. Heating and Cooling Requirements
Houses incorporating the above energy efficient elements should require relatively small heating systems—typically less than 50,000 Btu/hour, even for very cold climates. Some use nothing more than sunshine for the primary source of heat energy!
Common choices for auxiliary heating include radiant in-floor heating from a standard gas-fired water heater, a small boiler, furnace, or electric heat pump.
Additionally, any common appliance that gives off “waste” heat can contribute significantly to the heating requirements for such houses. Masonry, pellet, or wood stoves are also options, but they must be operated carefully to avoid “back drafting.”
If an air conditioner is required, a small (6,000 Btu/ hour) unit can be sufficient. Some designs use only a large fan and the cooler evening air to cool down the house. In the morning, the house is closed up, allowing it to stays comfortable until the next evening.
Unique Home Solutions has been optimizing energy efficient homes in Cleveland, Columbus and Indianapolis since 1983. We are experienced in evaluating and renovating homes based on our first-hand knowledge of the local climate. Contact us today for more information about making your home more energy efficient!