Home Energy Monitoring and Management
Most homeowners have experienced a breathtaking energy bill or two, especially during high summer or the dead of winter, when energy usage and costs often soar. In an effort to reduce costs and increase the efficiency of their homes, more people are exploring the option of home energy monitoring and management via the many systems available for automated home control.
Before you replace windows and doors, insulate the attic or install new siding, find out exactly where the home is leaking energy and dollars. The best way to do this is to get a home energy audit-- an evaluation of your home's energy performance. Energy audits generally cost between $250 and $350, depending on how long it takes for the energy auditor, or rater, to get to your home.
Jeff meets with the energy auditor
Jeff Wilson paid $350 for a Home Energy Rating System (HERS) audit, which is administered by the Residential Energy Services Network (RESNET). RESNET trains HERS raters to evaluate the energy efficiency of your home, and they come prepared with tools to help you decide where to start making repairs. "The nice thing about a HERS rating is that it gives you a cost-benefit analysis so you can make better decisions," Wilson says. Wilson learned he might as well be leaving a window wide open, year-round. That's how much air was passing through all of the leaky joints and weak walls and windows of his home. It didn't help that when he knocked out a knee-wall in his kids' bedroom to construct a built-in bookcase, he didn't properly seal the area. A daylong visit from the HERS rater covered every mechanical aspect of the home (HVAC, appliances, lighting) and its envelope (windows, doors, insulation, roof). The rater conducted a blower door test to assess the leakiness of the house, and a duct test to locate leaks in the HVAC duct system. He checked electrical outlets -- for, yes, more leaks -- and compiled all this information into a handy report with charts.
Jeff Knocks a Hole in the Kids' Bedroom Wall
Wilson learned he might as well be leaving a window wide open, year-round. That's how much air was passing through all of the leaky joints and weak walls and windows of his home. He didn't know it at the time, but he had made matters worse when he knocked out a knee-wall in his kids' bedroom to construct a built-in bookcase (as seen in this picture). That's because he didn't properly seal the area afterwards.
Diagnosing the House
Here are some highlights of Wilson's HERS test, what the rater determined about the home's efficiency, and what you might experience if you enlist a HERS auditor. Blower door test: A fan mounted inside the doorway is connected to a digital pressure meter. This way, it can measure any air escaping or entering the home. This is how Wilson learned that his home's "holes" amounted to 160 square inches of total open space—a sizeable gap. Infrared imaging: Wilson got his HERS test in the summer, so the rater used an infrared camera to show where heat was leaking into the air-conditioned home. Humidity is a problem in his region, and the reason most people crank up the A.C. during summer weather, Wilson says. So keeping humidity out can reduce energy use to keep the home "cool," when really the A.C. is mostly removing moisture from the air. Electric outlet tests: By testing individual switch plates, Wilson learned that their recessed lighting is an energy suck.
The HERS rater collected data from tests and, using a software program, compiled a detailed report to help Wilson understand exactly where his home stood on the efficiency spectrum. The Wilsons scored an 87 HERS rating, with 100 being the HERS baseline. Higher than 100 means a home is relatively inefficient; a score of zero means the home uses only the energy it creates, such as through solar or wind power. Wilson wasn't disappointed with his score, 87, but with a goal of net-zero, he has a long way to go with his Deep Energy Retrofit (DER) plan.
Energy Star Insulation
Interested in making energy efficient upgrades, but don't know where to start? Many municipalities and utility companies offer rebates or free energy audits under a variety of programs. Search www.dsireusa.org, the Database of State Incentives for Renewables & Efficiency, to find out where these programs are available. You'll find a map where you can search your area for HERS rating or other energy audit offerings. RESNET also administers online home energy surveys. "There is so much conflicting information about the best, least-expensive solutions, what homeowners should do, what contractors should do," Wilson says. "By checking incentives, you can find out which items on your HERS list you could do at a vastly reduced rate right now."
Maximize Your Audit
Wilson suggests these tips for making the most of a HERS test:
- Monitor your home energy use before the HERS test, preferably up to 6 months in advance. This gives you historical data to provide the rater.
- Be at home during the audit so you can discuss your goals with the rater.
- Ask lots of questions during the process.
- Request a range of testing information, from the actual energy use data to solid steps you can take in the short-, medium- and long-term to tighten up your house.
Wilson's rater used a thermal image camera to check the heat leakage around the recessed light in the top of the cabinet in the main bathroom. Wilson learned that recessed lighting can be one of the worst culprits in air leakage into unconditioned space and is correcting it as part of his DER. The Wilsons will have another HERS rating done in early winter to determine how effective their DER was in eliminating leaks. Their goal is to get a score of zero.
One step to consider taking before you begin exploring options for home energy monitoring and management is a home energy audit. Provided at low cost or even for free by many power and lighting companies across the country, a home energy audit may give you a good baseline for how energy efficient your home is. The audit can help you uncover any particularly glaring inefficiencies to address prior to implementing a monitoring system.
Once you've gotten a good picture of your home's overall energy efficiency, you'll want to consider what type of energy monitoring and management system is right for your home. Systems range from affordable, simple and easy-to-install to highly complex and extremely expensive.
At the lowest tier in terms of complexity and cost are the outlet-based energy monitors. These operate like power strips and plug directly into your home's wall outlets. You then plug any appliances near the outlet into the monitoring device, and the device will monitor and display the amount of energy being used by each appliance. This way you can determine where the energy hogs in your home are located (hint: TVs and computers are big offenders) and closely monitor how often they're plugged in and sucking up energy.
Next up in terms of cost and complexity are whole-house power monitors. These devices will integrate with your home's electrical grid and monitor your energy use centrally. You can enter information about the devices you want to monitor, as well as your current energy costs, and the device will calculate how much energy you're using and what it's costing you. Some of these devices can even give you information about high usage patterns and compare against variables like weather to tell you if you're using too much energy. Recent models have begun to feature wireless technology, so they can report information to a hub device or to your computer, tablet of smartphone.
The most advanced, complex and expensive option is to integrate your home energy monitoring and management with a whole-house control system. These automated home control systems combine control and monitoring for several common home systems, like lighting, security and sprinklers. Opting for energy monitoring and management as a feature of an automated home control system can be an extremely convenient approach, as it may offer the ability to account for all of the home's various systems as opposed to the more basic monitoring of electricity or heating and cooling provided by standalone systems. While the overall cost for an integrated system may be significantly more, the cost savings over time can also be significant since the levels of control and monitoring provided will be both more complex and more efficient.
See Also: How to Plan a Home Control System
- Home Control Term Glossary
- Home Automation: Control Your Home With Your iPhone
- Smart Appliances
- Lighting Controls
- What's Next in Home Control?
- What are Zigbee and Z-Wave for Home Automation?