Question

How much energy is saved by turning down a thermostat even by 1 degree? Is there a statistic available?

Asked by Gerry Jones
Hudson, OH

We are trying to motivate our retirement community to lower their apartment temperatures. The average apt. is 1500 sq. ft.

Answer

Michael Holcomb

Answered by Michael Holcomb

Byron Center, MI

Alliance for Environmental Sustainability (Headquarters)

February 8, 2012

Gerry this is actually a great question but the whole responsible answer is more complicated.

Let's start with industry figures.

  • For every degree you turn down your thermostat (and leave it there) you save between 1 and 3 percent of your heating bill (not to be confused with your gas bill if you have a gas dryer, range and/or clothes dryer).
  • If you set the temperature back for non occupied hours you won't realize any savings.

Retirees value comfort over energy bills?

Since your question concerns a retirement community I would guess that your occupants put a higher value on comfort than they do on energy bills.

If you want to encourage occupants to lower their thermostats a few degrees you will need to address comfort problems in the units.

  • The big issue is convection, resulting in drafts at floor level as make up air is drawn through the rim/band joist or fenestration rough openings to make up for air passing through the ceiling.
  • If you want to do a quick check to see if convective heat loss (and resulting drafts) are a problem measure the temperature difference at the baseboard, half way up the wall and at the ceiling.
  • If the temperature between the floor is more than 2-degrees lower than at the height of the wall thermostat your clients will be uncomfortable.

Stopping the draft

If you address the ceiling with advanced air sealing and the rim/band joist with spray applied, open-cell foam you will significantly reduce drafts and improve comfort.

You will also see a remarkable reduction in your heating bills because stopping air exchange keeps the heat indoors where it belongs.

My own home as an example

The best example I can give is my own home. I live in a 1950's 1,500 square feet ranch.

  • My wife kept the thermostat at 73-degrees in the winter months; anything less was uncomfortable for her.
  • I removed R-60 of cellulose and replaced it with 8-inches of open-cell foam (R-32) and insulated the rim/band joists with spray-applied, open-cell foam insulation.

Stopping the convection associated with stack effect resulted in an immediate improvement in the comfort level.

  • My wife is now as comfortable with a winter set point of 64-degrees as she was at 75-degrees.
  • The amount of propane we used to heat our home dropped by an eye-popping 84-percent. A win for both comfort and the wallet.

Had I tried to reduce heating costs by simply lowering the thermostat without addressing the real problem it would have been a failure and added stress to the family.

So if you want to incentivize people to lower their thermostats you'll need to make sure that the real problems have been addressed first.

 

For more information:

Read "Is there a standout spray foam insulation brand? Or one to avoid?" a Q&A answered by David Edwards.

Tagged In: heating cooling

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