The Green Home

Older homes can have low energy bills too

Posted March 22, 2010 5:17 p.m. EDT

“Having an older home, we felt that an Energy Remodel was the only way to keep our home up to date and provide us with a healthier living environment that we can enjoy for years to come. It worked; my son’s allergies just disappeared and we’re saving over 30% on our energy bills.”

Doug & Elizabeth Townsend – Durham, North Carolina

Older and historic homes may have plenty of character, but they also tend to have high energy bills. And because updating the building may be a little more complicated than a newer home, many homeowners believe that there is little they can do beyond turning down the thermostat, changing out the light bulbs, and continuing to sign those checks to the utility each month.

But from my experience of working with older and historic homes, the poor energy performance of older buildings can actually be a real opportunity. I regularly see homeowners achieve savings of 20% or 30%, and it’s possible to achieve even more. And when you are facing massive energy bills each month, 20% can seem like a lot!

But it’s important to remember that changing one thing in a building can always have unintended consequences elsewhere, and this is particularly true of older structures. (Over sealing the building envelope, for example, can lead to build up of moisture.)

Making sure that your contractor understands your home as a complete system is of crucial importance.


As technology has improved, as building codes have been tightened, and as the discipline of building science has developed, the concept of what we expect buildings to do has been turned completely on its head. A home built back in the 1920s, before the days of HVAC, would have been constructed to allow free flow of air and to avoid moisture build up. You can’t just install a HVAC unit on a home like that and expect it to perform well – the building envelope is just too leaky.

Many older homes may not even have floor insulation, so installing some simple fiber glass batting or high-tech spray-foam insulation can have a massive impact on energy bills. Even homes built back in the 1990s are, to some degree, behind the times. The last ten years has seen a revolution in our understanding of how moisture interacts with buildings – and that paradigm shift has lead to an emphasis on sealed crawlspaces and better vapor barriers. Contrary to what many folks think, addressing moisture issues in the crawl space doesn’t just tackle air quality or structural issues either, it will actually improve energy performance.


It’s not uncommon for a HVAC unit installed ten years ago or so to be rated at 8 to 10 SEER. (SEER stands for Seasonal Energy Efficiency Ratio, and is the standard measurement of efficiency for HVAC systems.) And yet building code for new construction specifies a minimum of 13 SEER, with the Government’s Energy Star program specifying at least a 16 SEER rating. In fact, high efficiency units are now available that achieve 19 SEER or even more.

Sometimes even the way a unit is installed can make a significant difference – most units that are 3 years old or more were installed without proper air sealing of the ducts, so even if you have a relatively new unit you may want to have it checked over.


It is always important to understand the complete picture when it comes to investing in your home energy performance. Because home building has gotten more standardized over the years, it can be a relatively easy process to ascertain what needs to be done on a newer home – often a visual inspection will be enough to assess the state of insulation, draft proofing, HVAC etc.

But older homes present a more complex challenge. Wear and tear can lead to structural defects, building codes may have been different or even non-existent, and there several upgrades and modifications over the years that complicate things even more. Even architectural features like gables and dormers, which create so much character in a historic home, may have unexpected effects on air and moisture flow – and that means they impact on how much you spend heating and cooling your home!

For that reason, I recommend asking your contractor about doing a complete energy audit of your home before investing in any major improvements. Energy Auditors use sophisticated tools like computer modeling, infrared cameras and blower door tests (essentially a giant fan that sucks air through your building) to determine how air and moisture move through your home. The result is a complete picture that provides a road map to greening your home – allowing you to invest your money where it matters most.

There’s no reason to be stuck with high energy bills just because you live in an older home. But be wary of throwing good money after bad. To get real results, and to update your home without losing its character, take some time to understand your home as a complete system. The small upfront investment of time and money will pay itself back in no time.

About this Blog:

Bobby Ferrel, founder of Green Horizon oversees The Green Home blog. Ferrel is co-founder of Green Horizon, with offices in the Triangle and Charlotte, offering home owners and builders a one-stop shop for energy efficiency and green building. Services include home performance assessments, weatherization, closed crawl spaces, all types of insulation, HVAC and geothermal installation and maintenance. Reach Bobby directly at or visit him online at