A Home Energy Audit — The Value

There is lots of discussion about Home Energy Audits. Utility companies may be providing them to their customers. You can find sources locally and nationally to provide you with one. There are sources online, and several outfits that will sell you a kit to ‘Do It Yourself’!   What should you expect from and audit? Is it worth the expense? Today’s post covers one audit and the results.

A homeowner called wanting to get a handle his old drafty 2 story all brick home.  He thought insulation in the un-insulated walls would help with heat and with the drafts.   He also wanted to know what else might work, and he was interested in how quickly any investment in his home might be recovered with savings from heat or cooling bills.

My visit revealed a nicely maintained home, with minimal energy efficiency beyond the current building practice of 90 years. There had been a few things done in the 1930’s and in the 1980’s that helped.

In discussing the concerns of the family, it was clear they liked their home very much. They had lived there long enough that through re-decorating, gardening and life – it was their home. Comfort issues were not the first concern. There big question was ‘what can we do to save some money?’.  In discussing that, the living room was mentioned as the room that was hot in the summer and cold in the winter.

The audit visit collected data from observation, my tape measure, some pictures.  I looked up in the attic, down in the basement as well as out and around. The furnace, AC and water heater were inspected. The manufacturer had issued a ‘Heat Rise” specification, so testing for that was part of the audit. There was a conventional water heater, and we did a ‘Worst Case Combustion Air Zone” test.

Finally, we would use a Blower Door and an Infrared Camera to measure and locate the potential drafts.

I found some insulation in the attic spaces, and confirmed the homeowners concern of un-insulated walls.

The furnace was within specifications heat rise.  The Worst Case Combustion Air Zone test passed.  The details on these tests and their meaning for a homeowner will be the subject of future posts.

We ran the Blower Door Test.  This test allows us to simulate a 20 mph wind on all 4 sides of the home and the ceiling at the same time. After running the test, standardizing the numbers for temperature difference, and accuracy; the house tested with a Natural Air Exchange at 1.3 times per hour.  The recommend rate without any type of added ventilation is 0.35 times per hour.

With the data collected, a computer model of the energy use in this house was created.  This showed insulating the basement would return the cost in about 5 years. Sealing the leaks revealed by the blower door test would pay off in about 10 years. The leaks were in the basement near the 1st floor; between 1st and 2nd floors and at the ceiling of 2nd floor or 1st floor where it was attic above.

Increasing the R-15 to R-60 in the attic would take 11 years to pay off. Improving a wall on the 2nd floor between a hall and the attic about 20 years to pay off.  And the exterior walls to be insulated would take about 99 years to pay off.  These periods all use the current utility rates, with no price inflation.

The homeowners contacted several contractors to obtain actual prices on the various improvements.  They chose to do some air sealing, insulate the basement walls, the attic, and the wall between the hall and the attic, and to install a new furnace and air conditioner.

After the work was complete, I returned to do a verification audit of the work. The new Blower Door test showed the planned 25% reduction was reached.  The HVAC installation included a new return line to the living room, which has reduced the temperature difference, so the room is no longer shut off on warm days in the summer or cold days in the winter.

BeforeBelow are two before and after infrared images. They show the 2nd floor hallway from the same point. The before picture was taken in February about 11:30 am.  This hallway is on the east side of the roof peak.

 

AfterThe after picture is taken in June about 5:00 pm. The February outside temperature was 46 degrees; the June outside temperature was 98 degrees. Both images were taken with the blower door moving air from inside the house to the outside; simulating a windy day.

 

 

The center of the clipped ceiling (diagonal slope) measures  78 degrees  in the before picture. In the after picture it measures 97 degrees.  So the outside temperature of 45 degrees before  work translated to a 33 degree increase passed through the deteriorated insulation.  After work 98 degree outdoor temperature translates to a 0 degree increase passed through the air sealed and new insulation.

If you look closely the air sealing could have been improved. The planned 25% decrease was accomplished.  It would have been nice to exceed the plan.

What good are the results?  The increased insulation is allowing the AC to work a whole lot less!  If the home had a 33 degree increase in June as it did in February – summer in Wichita would have been miserable in that home.  Also when the new furnace was installed the contractor running the new return to the living room, found a old return in the room that had no duct work. So he hooked up to that return grill for less than planned.  The living room is now comfortable.

Will your Home Energy Audit achieve these kind of results?  Perhaps it will!  If you would like to find out – give us a call.  We would be happy to discuss in more detail how your Home Energy Audit would work.

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