| Case Study of Energy Savings for 2 Bank Buildings|
|Architectural roll-out work is one of my specalities. In case you don't know what that means, it is when a client needs a lot of the same buildings all over the county. Mostly this is restaurant architecture but in this case the client was a bank. What I like about this work is that is gives me chances to do experiments comparing one method to another. This article is about one of those experiments. I think you will find the results interesting. For this calculation I use $0.09 a kilowatt-hour and $1.00 a therm, both prices have fluctuated above and below these averages but I don't think it affects the out come on the experiment.|
It all started when I was designing a lot of banks in the Chicago area. These were retail branch banks about 4,100 square feet each. The first one was located in Deerfield, IL and was a good quality commercial building that met all energy codes. The building had a steel frame infilled with 6 inch metal studs, filled with 6 inch fiberglass insulation for the walls, the roof was metal deck and bar-joist with 3 inches of insulation board. The second bank was in Wheaton IL about 20 miles away, so both building get the same weather. We only changed 3 elements, the buildings were other wise identical. One, we used different wall insulation we changed from fiberglass batt insulation to foamed in place low density polyurethane insulation the insulation value changed from R-18 to R-20, the real difference is the air infiltration into the building. The foamed in place insulation expands and sticks to everything sealing the walls tight. Two, we doubled the roof insulation from 3 inches to 6 inches, increasing the insulation value from R-18 to R-36. Third, the glazing was changed from 1 inch sealed glass units with clear low-e glass to 1 inch sealed glass units with tinted low-e glass. Each item was bid as an additive alternate so we could obtain hard numbers for what each item cost and not just rely on estimates. The foamed in place wall insulation cost an additional $9,150, the roof insulation cost an additional $5,300 and the tinted glass cost an additional $3,800, for a grand total of $18,250 or put another way that is $4..45 a square foot. Next I tracked the energy consumption for a year and put together a comparison chart to see if it was money well spent. I think the results are very compelling but you can judge for yourself. Electrical consumption was cut by 25% and gas consumption was cut by 62% saving $5,090 in the first year. That is $424 a month every month.
Now for some reason people always ask about pay back on energy savings, that is the wrong question, but the answer is about 3 years 7 months. The correct question is what is the affect on cash flow, and the answer is $283 per month for 20 years then it jumps to $424 per month. This is the correct question because building are financed and not bought for cash, the original $18,205 borrowed at 7% for 20 years cost $141 per month. $424 in savings take away $141 in dept payment is positive $283 a month. If you are not financing construction but paying cash a better way to judge the economics of this would be return on investment. In this case we invested $18,250 to get a return of $5,090 for a cool 28% return on investment. Can you match that by keeping your cash in the bank.
I have now made each of these items standard in my projects and with this data I have no trouble convincing clients it is money well spent. One last thing the client released me to share this information but not the bank name. I hope you understand.
Burt Andrews is an Architect with over 20 years of experience in designing restaurants and retail stores. You can read more of his restaurant ideas [http://archisaur.us/] and about restaurant architecture [http://archisaur.us/] at his blog. He is a principal at Larson and Darby Group in charge of the St. Charles, IL office.