Your Home Energy Audit - How to Assess Your Home Energy Efficiency
You can't escape the rising cost of energy. But you can reduce the amount you spend on utilities by making smart choices about home energy use.
One of the first steps to becoming a savvy saver is to learn how much energy you're already using - and how much energy you're wasting. To do this, you'll need to conduct a home energy audit. This basic energy assessment will be the foundation for your plans to improve your home's energy efficiency.
To start, gather your utility bills from the last 12 months and visit theEnergyStar Home Energy Yardstick to get an idea of how your home's energy efficiency compares to similar homes in your area. This will give you an idea of how much you need to do in order to improve your savings.
Once you've got your score, it's time to take a serious look at your home's potential energy wasters and find the places you can start saving money.
Finding and Stopping Leaks
Since up to 80% of our energy costs go towards heating and cooling our homes, it makes sense to ensure our homes aren't letting all that climate-controlled air escape. A home energy audit starts by assessing the structure of your home and locating places where drafts enter. Finding and eliminating these leaks can reduce energy consumption by as much as 30% a year (U.S. DOE).
To find leaks, walk through your home looking for drafts. Places to check for drafts include:
- places where two different building materials meet (corners, a wall and a chimney, around the foundation)
- window and door frames
- mail slots
- doggie doors
- electrical outlets and switch plates
- faucets and pipes
- any other place where gaps might occur
Pay particular attention to doors and windows. If windows rattle when you shake them, or you can see daylight around the door or window frame, then you should seal these leaks with caulk or weather stripping. Make sure you repeat this check when you put in your storm windows for the winter!
To help pinpoint troublesome drafts, you can undertake a building pressurization test:
- close all exterior doors and windows, plus the fireplace flue
- turn off your gas-burning furnace and water heater, along with any other combustion appliances
- turn on the exhaust fan in your kitchen and/or bathroom, or use a large window fan positioned to suck air from the building
- use a lit stick of incense to detect increased air flow - watch for the smoke to waver to signal an unwanted draft (be sure to be careful of curtains and other flammable objects!)
- or, wet your hand and wave it near potential leaks - your damp hand will feel cool when it encounters a draft
Once you have pinpointed the leaks in your home, seal them appropriately:
- caulk for small cracks and gaps
- expanding foam for larger holes
- weather-stripping around windows and doors
Check Your Insulation
The next stop on your home energy assessment is insulation. Heat flow is the natural tendency of heat to move from a warmer space to a cooler space. This means that in winter, the heat that flows out of your home must be replaced by your furnace. And in the summer, the heat that flows into your home must be removed by your air conditioner. Insulation provides resistance to heat flow, ultimately reducing your heating and cooling costs.
When conducting your home energy audit, you'll want to ensure your home insulation meets current recommendations. Check to make sure insulation is in good condition, and the material isn't compacted or crumbling. Old insulation isn't as effective and should be replaced.
Insulation should include a moisture barrier such as tarpaper, a plastic sheet or even vapor barrier paint on interior ceilings. Too much moisture will reduce insulation's effectiveness.
You will want to check the insulation in attics, basements and interior walls. Different regions have varying recommended levels of insulation. EnergyStar provides a easy-to-read map to determine if your insulation is sufficient for where you live.
- In the attic:
If the insulation is lower the attic floor joists, you probably need more insulation. Also check to make sure the insulation covers ductwork, pipes and the chimney.
- In the basement:
If the basement is unheated, you'll want insulation under the floor of the living area. For heated basements, you should also have it in the foundation walls, around the water heater, furnace, pipes and ducts.
- In exterior walls:
To check the insulation in your walls, turn off the circuit breaker and remove the cover plate from a wall outlet. Push a long stick - if you meet resistance then there is some insulation in the walls.
The next step in your home energy audit is to determine how much energy you are using. While your monthly bill will give you an overview of consumption, it can't tell you which appliances, devices and gadgets are drawing the most power.
To approximate energy use for common appliances, visit Michael Bluejay's Saving Electricity site, where you'll find a handy calculator for electric costs.
But for a more exact evaluation of your personal electric use, invest in a few smart plugs or smart power strips that monitor the actual energy consumption for individual appliances and devices. You'll probably be surprised at how much energy appliances draw - even when not in use! So-called "vampire devices" - stereo and TV equipment, computers, cell phone chargers - continue to pull energy even when they're turned off.
While you're checking your appliance use, spend some time evaluating your lighting too. Lighting can account for up to 10% of your home energy use. Are you using 100-watt bulbs where 60 or 75 watts would do? Better yet, switch to CFL or LED lighting for even more energy-efficient savings.
Heating and Cooling Systems
Since heating and cooling account for a significant portion of our home energy costs, it's worth some time evaluating your system's efficiency when you do your home energy audit.
How old is your air conditioner and/or furnace? If it's more than 15 years old, it is probably worth replacing. Technological advances have led to better performance and efficiency, which means they cost less and operate better than older systems.
When is the last time your system was serviced? Heating and cooling systems should be professionally serviced once a year. Filters should be cleaned or replaced once a month, especially when in periods of high usage.
Are the ducts clean and insulated? If there are dirt streaks near seams or vents, chances are there are air leaks in the ducts. Make sure they are sealed with duct mastic, and that any ducts that travel through unheated spaces are insulated.
Professional Home Energy Audits
While you can get a good idea of your home's energy efficiency on your own, you can also bring in a professional to conduct a home energy assessment for you. Professional energy auditors have access to equipment like blower doors and infrared cameras that can precisely evaluate your home's energy efficiency. Many times utilities provide these services to their customers for a discount or even no charge. Or you can hire an independent contractor capable of making specific recommendations for about $200.
For more information and recommendations about home energy efficiency, you can also visit the Home Energy Saver calculator from Berkeley Lab. This free online tool will help you find even more ways in which you can improve your home's energy efficiency and start saving money on your utilities.