It’s not easy to transform a house that’s an energy hog into a model of energy efficiency. The improvements involved in achieving this major energy makeover have come to be summarized as a “deep energy retrofit.” When you begin to grasp how extensive and expensive a typical DER can be, it’s easy to understand why we aren’t seeing more of them. But that needs to change, mainly because of the following factors:
- Over 40% of the total energy consumed in the U.S. every year goes toward “operating” our buildings –heating, cooling and electricity use. That’s a pretty major chunk of our energy budget. By contrast, transportation only accounts for 28% of our total energy consumption.
- Many of our houses use twice as much energy as they should, and we’ve actually got some 58 million older homes that aren’t insulated at all.
The main objective of a DER is energy efficiency –reducing a building’s electricity and fuel requirements by anywhere from 50%-95%. A typical DER begins with insulation and air-sealing upgrades. Basically, the goal is to turn a leaky, poorly insulated “building envelope” into a superinsulated shell that’s as airtight as possible.
Once the building envelope has been improved, the HVAC system that used to provide adequate heating and cooling is going to be oversized and inappropriate. So it can be replaced with a smaller, more-efficient system designed for tight, well-insulated buildings.
While building envelope and HVAC system upgrades comprise the main aspects of a DER, other improvements are also typically part of the picture –like improved ventilation for better indoor air quality. Newly installed finish materials (siding and interior wallboard, for example) should resist mold and moisture damage while also offering longevity and low maintenance.
It sounds attractive, doesn’t it? The trouble with Deep Energy Retrofits is that they’re expensive and very challenging in terms of carpentry and remodeling requirements. How do you turn a standard 2x4 wall with R-13 insulation into a thicker airtight wall that contains R-40 insulation? When you make the wall thicker, what happens around window and door openings? How can you upgrade attic insulation when a room has a cathedral ceiling?
Building technologists and contractors are working on solutions to these problems. You’ll find ample evidence of this enterprise if you Google “deep energy retrofit.” And even amidst the budget cutting that’s taking place at national, state and local levels, there are some encouraging success stories out there --DER projects completed with grant money that’s still available. Let’s hope that this work can continue. In terms of energy use, our existing housing stock can be an anchor that drags us further down into fossil fuel dependency, or a transformational opportunity that makes homes more affordable to own, while reducing environmental damage and encouraging innovation and job growth.