If you use or plan to use a ductless mini split in your home, a home energy audit will pinpoint the areas of your home where you have energy losses, either through inadequate insulation, air leakage or other problems. Following through with the findings and making the needed improvements will lower the amount of conditioning your home or space needs.
How a Mini Split Heats
Since the mini split is a heat pump, it can both heat and cool your home. While ductless mini splits offer high cooling and heating efficiency, they work better - especially in the winter - when the home is airtight and adequately insulated. The ability of the mini split to heat depends on the climate in which you live and the heating seasonal performance factor (HSPF) of the mini split. The current minimum HSPF available is 7.7, but mini splits that use scroll compressorsexceed that minimum and can create much warmer air. Improving your home's energy efficiency and selecting a mini split with an HSPF adequate for your climate will help you rely on the mini split through the heating season.
The Energy Audit
A licensed energy auditor uses a battery of tools to measure the efficiency of your home. The audit includes a thorough inspection of your home's components that include:
- Attic and wall insulation
- Windows, their quality and seal
- The HVAC system, including the ductwork
- Lighting fixtures, especially recessed lights that protrude into the attic
- Fireplaces or wood stoves
Besides physically examining your home, the best audits include a blower door test that measures the amount of air infiltration inside your home and where it occurs. Auditors typically combine a thermographic analysis of your home to show where the leaks occur.
Blower Door Test
The blower door is an appliance that contains a powerful fan inside an adjustable frame, as well as a manometer that measures the falling air pressure. The auditors fit it tightly inside the door frame and after closing all the windows, extinguishing any gas-burning appliances and opening interior doors, start the fan. During the home energy audit, the blower door depressurizes your home and the rate at which the pressure falls gives them information about how leaky your home is. Homes with lots of air leaks lose pressure slowly, while a tighter home loses pressure quickly.
Thermographic cameras can be either still or video, and show where the thermal differences are during the blower door test. The leaks will show as different temperatures and their color depends on the season in which you have the home energy audit. If the temperature indoors is close to the outside temperature, the energy auditor may ask you to either heat or cool your home so there's a 15 degree difference between the indoor and outdoor air. During this phase of testing, the air leaks will be clear and can come in any of the places where pipes, wires or other infrastructure enter or leave your home. Sealing them with caulk, expanding foam, weatherstripping and other materials will drop your conditioning load and help the ductless mini-split system operate far more efficiently. The thermographic scan of your home also shows where insulation levels are inadequate in the walls, floor and attic. Adding more will lower your conditioning load.
Last Audit Steps
Once the home energy audit is over, you'll have all the information you need to tighten up your home and deal with areas that have inadequate insulation. Air sealing with caulk, expanding foam and weatherstripping takes care of problems associated with leakage around doors and windows. If you use expanding foam outside, you'll have to paint it so it doesn't degrade under direct solar exposure.
Adding new insulation to attics is relatively easy and inexpensive, but if you have problem areas inside your walls, you may need a professional who can blow loose insulation into them, or use expanding foam.
Improving the energy efficiency of your home or the area the mini split conditions will reduce how long the system needs to run, which increases its life and lowers your energy bills year-round. It also improves the indoor air quality of the space the mini split conditions.
To learn more about a home energy audit and how it benefits a ductless mini split and lowers conditioning bills, contact us to find your local Mitsubishi Electric Contractor.