Home energy audit

Home Energy Audit

A home energy audit is an energy assessment process aimed at identifying potential energy consumption inefficiencies by home electrical appliances. It is the first step to take if you consider going solar. But even if not it's a sane step to take to save unnecessary overheads on your energy bills without sacrificing your comfort. The last part is worth mentioning again, you do not have to cut down the heating or cooling time or otherwise cause discomfort to house members by spending less energy. The aim is to eliminate the consumption that's wasteful. The energy audit identifies and tries to reduce consumption by improving building envelope insulation, eliminating excess lighting and air leakage. For an accurate energy audit, it is best to hire a specialist but armed with the right tools and determination you can also do it yourself. The tools commonly used for energy audits are described in our energy audit tools article.

If you plan on installing solar panels to harness the Sun's energy then for each dollar spent in energy efficiency measures you'll save much more on solar system costs. For example,

if you can save just 0.5 kWh per day on your power bills, your solar energy system may cost $2000 cheaper.

The actual number, obviously, depends on the panel prices, subsidies, and incentives but the impact is obvious. Another potential advantage of making your property energy efficient is that it increases the property's appraisals if you ever plan on selling it or renting out. One metric assessing the energy performance of an apartment/house is the Home Energy Score.

DIY Energy Efficiency Measures

If you have the time and vigor for it, doing it yourself will make you understand what makes your house tick. The point here is to understand that don't to chase after each inefficiency in your household but rather the glaring ones. According to Pareto's law, a few inefficiencies will account for most of the energy waste in your home so that's where you have to look first. Let's start with the big ones.

Plug The Leaks

Air leak

You can write-off 5 - 30% expenses off your heating and air-conditioning bill by simply plugging up air leaks.

A pressure test can help pinpoint the sources of drafts so you can trace them down and seal off. The easiest way to reveal air leaks in a room is to do a blower's door test but that requires expensive equipment and an auditor to operate it. A simpler alternative is to do a pressure test with an incense stick. Here's how you can do it: turn off the HVAC system, close the fireplace damper, turn off any furnaces and heaters. Close all the windows, vents and skylights if any. To depressurize the room turn on the exhaust fans. If you don't have exhaust fans then aim a portable fan out a single open window and turn it on. Now go around the room holding a lighted incense or a candle around windows, electrical outlets, switches, doors, molding interfaces, hatches, and so on. If the smoke fluctuates (or light flickers) then you've identified a leak source. Turn off the fans and get to work.

HVAC ductwork is another common source of leaks so follow it throughout the house and visually inspect for any rips or tears. To find the invisible cracks turn the system on to pressurize it and test with incense or candle as described above.

Check The Insulation

Check if HVAC ducts and hot water tubes are well insulated. Common places in a home where insulation breaches occur are light fixtures. Either change the insulation where it is damaged or fill it with expandable foam insulation. If you have a basement check whether the ceiling is insulated. The same applies to the attic, having the insulation in the attic thickened is the easiest. But if the insulation of the outer walls is substandard your best bet may be to simply put new siding on the outside of your walls. in this way, you kill two birds with one stone: your home will have a remodeled facade and be well-insulated all at once.

Service Home Appliances And HVAC System

If your HVAC systems, refrigerator or washing machine are old they are undoubtedly inefficient. If they are not old having them serviced or servicing yourself still may pay. For example, vacuum the coils of your refrigerator twice a year. When crud builds up on the coils, the compressor is much less efficient so it eats up a lot of energy. The same goes for ACs. When the filters get clogged up with dirt ACs draw more energy to keep the same temperature level. Besides cleaning the filters, schedule a serviceman to do a general cleaning with special detergents once or twice a year. 

Get Rid Of Phantom Loads

Phantom load or standby power is the electricity consumed by the devices that are turned off or in standby mode but still plugged into the grid.

Phantom loads cost the average US household $100 annually.

You can do a little experiment to uncover hidden current draws. Shut down your entire home's electricity by flipping the main circuit breaker in the fuse box. Is your meter still moving? If yes, call the power supplier because you may have current leaks. If the meter stopped then turn the switch back on and start turning off every electric and electronic device. If every device is turned off but the meter is still moving then you have phantom loads, start unplugging things. The common "culprits" are little gizmos with LEDs, TVs, stereos. Your cable box also draws a lot of current even when turned off.


Blinds are excellent insulators. The honeycomb variety works well both in cold and hot weather conditions if its sides are black and white. In colder weather you want the darker side to face the Sun so that it will absorb heat and warm up the room. The opposite lighter side will reflect the heat waves and keep them in the room. In hot weather, on the contrary, you want to deflect the heat waves coming from the Sun so you should turn the brighter side towards the outside world. In this case, it's better to put the blind outside a window because it still absorbs a lot of heat and if the blind stays in the room the heat will also stay there. You can put blinds over windows on the outside, which works much better in hot weather.

Shades And Screens

Solar shade cloth is similar to conventional screens, but it is thicker and has a specially designed mesh to impede IR and UV light. Blocking IR and UV waves makes a room cooler and prevents adverse health effects on humans. Solar shade cloth has more integrity and lasts longer. Newer fabrics let the light pass through without blurring it. In hot summer days, less lighted rooms feel cooler even if the room temperature is the same.

Utility Incentives And Rebates

If your utility rate structures include incentives and rebates why not leverage those? Utilities offer rebates for customers to replace old, energy-inefficient equipment with newer, more efficient ones. Rebates are sometimes tied to the physical device, such as $1 for each low-wattage fluorescent lamp used. Utilities offer such benefits because it is cheaper for them to save the energy and capacity for new customers than it is to build new power plants or new gas pipelines to meet the additional load demands. Additionally, there are rigorous environmental standards that deter them from building and operating new facilities. 

Direct incentives may be in the form of low-interest loans that can be paid back monthly with energy savings resulting from the more efficient equipment. Incentives may also be in the form of lower rates for the electricity used to run higher efficiency lights and appliances, and more efficient process equipment. Yet another form of incentive may offer free audits from the utilities. Your task is to find out about these benefits from your local grid and make good use of them.

Indirect incentives are often in the form of a special rate for service at a time when the utility is short of capacity, such as a time-of-day rate. The time-of-day rate offers a lower cost during the off-peak times, and often also during the off-season times. 

Programming Your Thermostat

As HVAC energy usage amounts to a substantial part of the overall household energy usage, leveraging time-of-day rates to run your heating and cooling systems makes a financial sense. Programmable thermostats can come to your "rescue". They offer several benefits

  • Make daily or weekly programs that turn your temperature up and down without your supervision. The program takes into account the energy rates for a particular time of the day at the same time maintaining a comfortable environment.
  • Manually override the automatic setting whenever you need it, if only briefly
  • An occupancy feature keeps the temperature at standby when there's no one home

Plotting Your Energy Usage Patterns

You are going to need your power bills data for the last 2-3 years whether you do your own energy audit or hire a specialist. Your utility will likely send you this data free of charge. Armed with this data, we can graphically plot it to aid us in the analysis process. To illustrate the point we will plot a real-life energy usage graph and try to make some observations on it. The sample data comes from a 4-member household outside of the US but the observations should also hold for a typical US family of the same size. The first plot is the monthly energy bill data for about 3 years. In this particular case, daily and nightly rates are different - an example of time-of-day or time-of-use (TOU) rate. As the nightly rate is lower the bills might have been lower if more heat/cooling were done at night rather than during the day. From the graph, one can also notice that the winter of 2016 was particularly cold in this area.

This next graph plots the data aggregated by month for the 3 year period. The dynamics is typical: the heater is on most of the time in winter, and the air conditioner in the summer. The next thing to notice is the baseline usage. That's the regular electricity consumption with heating and cooling energy usage factored out. In our case, it is about 200 kWh. This figure is of interest because it tells you how much you are spending on heating and cooling, versus the rest of your requirements. Another comparative metric we can calculate is the average kWh per day throughout the year. To calculate it just add up the total used kilowatts for a year then divide the result by 365. In this case we get 5556 / 356 = 15.22 kWh/day.
For comparison, the US average kWh per day is around 20kWh/day.

You can play around with the graph by clicking on the "Edit Chart" button, tweaking the data or plugging in your own.

Hiring A Pro

If you'd rather hire a professional to do the job you can head to a list of companies offering residential energy audit services. But before hiring a professional energy auditor, write down your own questions to ask and prepare to answer some questions the auditor will most likely ask:

  • Make a list of existing problems such as condensation or drafty rooms.
  • Have a summary of home's yearly energy bills for the last 2 - 3 years.
  • Is anyone home during working hours?
  • What's the average thermostat setting in hot and cold seasons?
  • How many people live in your home? Are there kids?
  • Are there any rooms that are mostly vacant?
  • If you plan to make any upgrades or modifications in your household, ask what effect will they have on energy efficiency.
  • Ask about any financing programs the company has for improvements the auditor suggests.
  • Ask about any guarantees for the auditor's work. How accurate they warrant the savings?

The answers to these questions may expose some easy methods to reduce your household's energy consumption. The auditor will produce a report detailing the uncovered energy conservation measures and recommendations. In that report, you can see where the energy is being wasted and prioritize your efficiency upgrades. Unless you act upon those recommendations the audit will have no tangible effect on your home. But if you do, you are likely to save 5 - 30% on your monthly energy bill while retaining the health and comfort of your home.