Best Practices: Conservation vs Generation

Mary EnglishUncategorized

Windmills are majestic. Photovoltaics are sexy. And ductwork, HVAC and insulation? What was that, you just said? – my eyes have just glazed over.

When it comes to taking sustainable actions on our buildings, it’s usually not the highest priority. There are multiple reasons for this: it seems complicated, a hassle, maybe expensive; and like other technical topics – kind of boring to most people.

But energy conservation in our built environment is very important. It is the vegetables compared to the dessert of energy generation in the sense that everyone relishes a sweet ending to the meal usually more than the nutrition that comes before it.  I realize that this analogy is not perfect – renewable energy is obviously important in our drive to reduce greenhouse gases. However, energy conservation can definitely feel like the broccoli of sustainability for those of us that have been representing its cause over the last several years.

If you do not retrofit – or design – a structure to be as energy efficient as possible, renewable energy generation just subsidizes the energy overuse of your building. Or putting it another way and using another analogy, which would you rather feed if you’re a pet lover on a budget: a Great Dane or a Minatare Pincher?

Take, for example, a common area of inefficiency in older buildings: under or uninsulated walls. If you take a typical small commercial building of 20,000 sf that may have an inch of old fiberboard insulation equaling to a thermal value of roughly two (way below modern energy codes) and retrofit that building to code in many areas – an R20 – this is what you can expect as an average savings calculation:

Sample Case Study:

20,000 SF Commercial Building. 70 years old.
Energy retrofit:   Thermal Value Above Grade Walls R2 to R20
Cost of measure:  $75,000
Energy Savings:    284,876 kWh’s energy reduction @ .10c/ kWh = $28,478/ year payback
Simple Payback*: 2.7 years

            *Cost of measure/ Energy Savings at current rates. No interest or increase calculated.

To get the same amount of energy savings with a solar array, you would be looking at needing a very large area of land for a 200-kW system at roughly 2.5 – 3 times the cost of the insulation installation. This may seem an extreme example, but it happens more than you would think.

Following through with this example – imagine the scenario where the building owner felt that adding insulation to existing walls was a hassle but decided to add solar anyway. This homeowner is now going to pay for the lack of insulation in the building; where the solar array could actually cover the plug loads of electronics, lighting, and some of the costs of heating and cooling otherwise.

In a study conducted earlier this decade, the American Council for an Energy Efficiency Economy (ACEEE) published a paper comparing different sources of energy to increasing efficiency, and this is what they found:

Energy conservation was clearly the big winner when compared to both clean, and more traditional – i.e. not so clean – power sources.

We live in a world ruled by the almighty dollar. If we acted solely on a rational brain, we would all see the benefits of adding more money to our savings accounts – even when we have to absorb short-term costs – rather than to the monthly check made out to the electric company. The energy retrofit investment is better than most capital investments on rate of return.

However, humans are not necessarily logical beings. We like pretty things. We like to follow through on ideas that excite our imagination. The market-place of new ideas where many of the green technological improvements live is a habitat for people that want to improve their sustainable portfolio.

Sustainability is always the right decision. Just follow the logic and the data: conservation – energy efficiency – first. Then at last we can really benefit to the fullest from all that renewable generation.

Mary English has been working in sustainable construction and building science for over twelve years. She has worked with multiple designers and builders in the Kansas City region testing and consulting on best practices from building envelope to HVAC. She currently serves as the Committee Chair for the USGBC Central Plains Programs Committee.