Attic - Walls - Floors - Basement - Crawl Space - Insulation

Energy Efficiency Case Study: Identical homes, 29% difference in Energy Bills.

Published by Admin at 9:02 AM under Blog


These neighbors have the exact same floor plan: 1200 square foot ranch, with 3 bedrooms and 2 baths. The one on the right, House A, pays about $240 a month for their energy bill, while the house on the left, House B, pays about $150 for the same time period. Over a three month time period, the two houses spent a combined total of $927 on energy bills, but House B paid $265 less than House A. House B paid 29% LESS in energy bills. So what’s the difference? We’ll give you a hint: it has very little to do with the inhabitants energy usage habits. 

House B was built with Energy Efficiency in Mind

House B worked with a standard builder, but insisted on using Affordable Comfort for insulation and energy efficiency measures.

In addition to some simple lighting changes (using LEDs instead of CFLs or traditional incandescent bulbs) Affordable Comfort used closed cell spray foam to air seal all of the top plates at the ceiling plane of House B. Then, R-49 cellulose was installed in the attic. The neighbor, House A, was stuck with the outdated code’s bare minimum of R-38. (Here’s an explanation of R-Value) House B was also fitted with a combination of closed cell and open cell insulation for the walls. House A was insulated with fiberglass, which is the cheapest and poorest performing insulation on the market. The walls were only insulated to R-11. Both homes have unfinished basements, but House B has insulation along the bandsill in the basement, while House A was insulated using fiberglass batt, which is totally useless for this application.These extra insulation measures left House B with a great Thermal Envelope, sealing conditioned air in, and keeping the house cool all summer long.

Meanwhile, over in House A, the summer was spent cranking the AC, trying to cool the front two bedrooms, which the owners claimed were hotter and more difficult to cool than the rest of the home. These two rooms are on the front of the house, furthest away from the air conditioner/furnace, which means conditioned air has a long way to travel. The path includes multiple turns, which causes a major loss of  energy and temperature along the journey. The air coming from the register this summer was not as cool and also suffered a loss of pressure. The extra sun beaming through the bedroom windows combined with the warm, low pressure air coming through the vents made the bedrooms incredibly difficult to keep cool.

Over the entire summer, House A paid a total of $510 in energy bills while still dealing with rooms that were not quite cool enough. House B paid only $300 and didn’t have any cooling issues.

Let's take a look at the difference in energy usage: 

House A:



House B:


So what happened with House A?

The owners of House A assumed that since they were getting a freshly built home, that it would be energy efficient. This is a common misconception. The truth is, builders are not insulation or energy efficiency experts. They operate off outdated building codes and only do the bare minimum. Builders worry about how the house looks, not how it works. 

Builders often have subcontracts with other professionals that do things such as provide/install HVAC equipment, windows, plumbing, etc. When the owner of House B tried to take energy efficiency a step further and choose their own Energy Star rated HVAC equipment and have Affordable Comfort install windows, the builder refused, saying that she had to use her subcontractors. House A was never offered any insulation or HVAC upgrades or options either.

The owners of House A decided to build their own home to fit their personal needs. They chose the area for the good school districts for their children, and assumed the builder would provide top quality insulation and energy efficiency measures. Unfortunately, that’s not exactly what they got. While House A and B look very similar, it’s clear that one home is more comfortable and more cost effective.

Talk to your builder, or talk to us.

If you are planning on building a new home, talk to your builder and insist upon energy efficiency measures. Not only will building smart save you money and make your home more comfortable, it will lessen your carbon footprint.

If you have an existing home, it’s not too late to make your home efficient! Give us a call at (314) 884-0092 or email us at and we will walk you through your options. You can also check out some of our great DIY Articles!

How to Keep Your Energy Bills Lower in the Summer

DIY Winter Repairs for a More Efficient Home





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