The Value of Building Collaboration

Return on investment has always been a key question when considering the value of building an energy efficient or green building.

Upon first glance many people dismiss adding green components to their home as too expensive with no perceptible increase in value. While there is no doubt that a green building is more energy efficient and comfortable, many do not consider these attributes offset the perceived increased costs.

Recently, AE Building Systems collaborated with Bonsai Design Build and Green Spot Energy and Sustainability on a project in the LoHi district of Denver that would indicate that consumers are changing their minds about energy efficient homes and are willing to pay for it.

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In late 2013 Josh Oqueli from Bonsai DB approached AE Building Systems with the goal of building a net energy zero spec home. Josh had a preliminary design, but wanted AE to develop the systems necessary to reach his goals. While meeting net zero can be as simple as adding a significant number of solar panels, AE advised Josh that investing into the building envelope would help reduce his solar and heating requirements. Additionally, this approach would have the added benefit of providing a significant upgrade in comfort to potential buyers over other homes in the area.

The plans were fleshed out to include structural insulated panels for a highly insulted building envelope. High performance windows were added to the insulating and air barriers. Reducing air infiltration is key in reducing energy use and increasing occupant comfort. AE suggested using an air and weather barrier that allowed drying of the envelope while making an air tight seal, that is a sort of a Gore-Tex© blanket for the house. The foundation was insulated on the exterior with mineral wool.  Lastly, an ERV was recommended for a continuous stream of filtered fresh air.

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The cost of these items did add to the initial budget of the project over more traditional building materials; however, increasing the thermal performance of the building envelope contributed significantly to the reduction of the heating and cooling system. The R-24 walls, R-42 roof, and R- 6.25 windows allowed Bonsai to install a small mini split heat pump system for both heating and cooling. Because these systems do not require ducting and the units themselves are inexpensive, the whole HVAC system was installed for around $13,000.00. The cost of this system was over 50% less than a forced air system.  These savings more than offset the upgrades to the building.

Bonsai DB recognized that certifying The Lipan St. Cottage would be key to verifying the efficiency of the home and capturing the value of the upgrades. They chose to bring on Green Spot to certify the home Energy Star. The results of certification were astounding. The cottage out-performed Energy Star in many categories, in particular, air sealing. Energy Star 3.0 requires an air change result of 4ACH @ 50 pascals. Lipan St. was a .59 ACH @ 50 pascals. That is almost 10 times better! Green Spot said they had never tested a home that tight!

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These results exceed the most stringent building program in the world, Passive House. Coupled with a 7 KW solar system, the home is net energy zero while allowing for one electric vehicle.  Just as significant, the comfort level in the house is extraordinary. At an open house earlier this year the HVAC was turned off because the body heat of the occupants was enough to keep a comfortable temperature in the home throughout the night.

Equally as important as the comfort and performance of the building was Bosai’s ability to sell the project in a timely manner at a price corresponding with the upgrades. It took less than 30 days for the home to go under contract at the asking price of $789,000. This was about a 20% increase over market.

Wisely upgrading the appropriate building systems allowed Bonsai DB to create a stylish, energy efficient building. By collaborating with the right team they were able to exceed their performance expectations while creating good value for the homeowner.

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-By Mark Attard

Mark Attard


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