Eliminating Energy Use in Existing Buildings: Easier Than We Think?

A few weeks ago, I gave a talk titled “Eliminating Energy Use in Existing Buildings: Easier Than We Think?”  It was to mark the release of Energy Audits and Improvements in Commercial Buildings.  We are already seeing many examples of successful new buildings that do not use energy, and I will keep discussing those here in Building Evidence. But the focus of a talk on existing buildings raised a few eyebrows and people have been coming to ask:  Can it possibly be easy to eliminate energy use in existing buildings?

Here is a summary of the talk:  (Skip to the bottom if you just want me to send you the presentation slides instead.)

  • Climate change is real. The widely-accepted goals of reducing carbon emissions by 80% by 2050 are important.  2050 is not far off. We need to get moving. And the task at hand may be … easier than we think.
  • I have now seen multiple examples of existing buildings that have eliminated energy use, or come close to it, and I described some of them in the presentation.
  • I showed examples of how when we set goals to save energy, we usually save as much energy as we want to save. The examples I gave are drawn from hundreds of buildings.  If we set a goal to save 20%, we usually do save around 20%, on average.  Not much more, not much less. If we set a goal to save 30%, we usually do save 30%, not much more, not much less.  If we set a goal to save 100%, I have seen multiple examples of where we do indeed save 100%.  And, conversely, if we set out even with the best of intentions to save energy in buildings, but do NOT set ANY goals, we usually save less than 10%.  Two takeaways:  If we set high goals, we can reach them.  Just as importantly, if we set low goals, or do not set any goals, we risk not saving much energy.  We also risk giving the false impression that we cannot save much energy, whereas in fact we canif we want to.
  • Technologies are readily available to eliminate energy use in existing buildings.  But we need to go beyond “one-for-one replacements”. For example, if we only change a low-efficiency lightbulb with a high-efficiency lightbulb, we might save 30%.  However, if we ALSO “right-light” a building (not overlight it) and if we ALSO install lighting controls (such as motion sensors), we can save well over 50%, and can often save over 90%.  These are both examples I have addressed previously in Building Evidence blog posts.  Recall the approach to light corridors that reduces energy use by 99%, that the building occupants love? In the presentation, I also gave examples for space heating, hot water, and ventilation.
  • To eliminate energy use in a building, we must do many things: Modify or replace the heating system … and the cooling system, and the lighting, and the hot water, and the appliances, and the insulation. We also need to address infiltration (air leakage) and ventilation.  Or at least we need to be ready to make changes to a majority of these.  We might get away by not doing all of them, but we need to do most of them.  Finally, we need to install renewable energy such as a solar photovoltaic system.  It is not enough to do one or two things.  Solar by itself ain’t enough. LED lighting by itself ain’t enough. High-efficiency heating by itself ain’t enough. We need to roll up our sleeves and get ready to make at least 5-10 major improvements. But, once we take this realistic approach, the technology is there to do it.  It does not even need to take long, we now have examples of the work being done in under one week.
  • From several case studies, I estimate the investment required to eliminate energy use in buildings to be approximately $50-$60/square foot, at present, or more. I believe over time this cost can be reduced to $40/square foot, or less.  The costs of many energy technologies have literally plummeted as we have achieved economies of scale:  from solar photovoltaic to LED lighting, to heat pumps.  I believe that if we only TRY to eliminate energy use in buildings, we will see substantial cost reductions.  But we’re not even trying, so costs are remaining way higher than they need to be.
  • Our current typical level of energy conservation investment (under $5/square foot) will likely limit us to savings below 20%, nowhere close to what is needed to slow or stop climate change. Again, once we get serious, it’s actually not that hard. Using a house as an example, if we are going to budget as little as a new fence or a new hot tub, it just ain’t going to happen, we are not going to come close to eliminating energy use.  If we budget seriously for energy work, as much for example as a nice new kitchen and maybe a nice new bathroom, now we’re talking about coming close to the budget needed to eliminate energy use.  $7500 won’t do it.  $75,000 will.
  • For the many of us who do not have cash on hand for this kind of investment, long-term financing is needed to eliminate energy use in buildings. Long-term financing such as refinancing a mortgage:  25-30 years. Short-term loans (let’s say 15 years and less) do not provide enough time to repay the capital needed to eliminate energy use.

Those were the main points I made.  I am happy to share the presentation powerpoint, which has a little more data – send me a message or e-mail, imshapiro at taitem dot com.  And as always let me know what you think.

Photo:  A beautiful stained-glass window in our office building.  Our building is now in a historic district. Can you see the interior storm window?  To me, this is an example of reducing energy loss by well over 50%, while maintaining the beauty of an old window. Who says we could not slash energy use AND preserve our beautiful old buildings?

 

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