Getting to Net Zero and Beyond

Walking Mountains Science Center, located in Avon, Colorado, dreamed for a long time of addressing the community’s affordable housing crisis by providing housing to some of its educational staff. High on their priority list was to design the housing to net-zero annual energy (meaning the buildings use zero energy from the grid yearly).

This project shows how we helped them create affordable housing that is both beautiful and energy-neutral following simple guiding principles.

Creating a high-performance building envelope

Section through the wall and roof to show insulation strategy.

The first half of the net-zero energy equation is a high-performing building envelope that minimizes heat transfer. Like a cooler, the inside stays comfortable in summer and winter without having to rely on big energy inputs.

Detailing the windows openings to ensure no air leakage.

The building envelope is the outside “shell” of the building (walls, roof, foundation, windows, and doors). The building code requires energy efficiency in these elements, but with an understanding of how energy moves through them, it’s not hard to be better than the code minimum.

T-studs showing the insides on the left and final form with foam insulation on the right.

Making sure that there were no “thermal bridges” (spots in the wall where the insulation was compromised), was critical to achieving a high-performance envelope. We used innovative products such as t-stud framing to ensure that insulation was continuous from the roof to the foundation with nearly no interruption. Next, we utilized a very effective self-adhesive weather barrier system from Switzerland to eliminate air leakage, which rolls on and sticks rather than being stapled like other house wraps. Window and door openings are sealed, and joints were filled with foam.

The insulated core of the t-studs is aligned with the insulated core of the window header.

Maximizing renewable energy

Like sunflowers, the buildings turn toward the sun and their elongated roof forms allow an entire extra row of solar panels

The second half of the net-zero equation is maximizing the amount of renewable energy produced to offset the energy needed. Two methods were used with no additional cost. First, we designed the roof with an offset ridge, making the south-facing part of the roof larger for more solar panels. The second was orienting the buildings so the roofs faced south.

Finally, to balance the equation, we chose to make this an all-electric home. We used cold-optimized heat pump technology to provide both heating and cooling. This technology has advanced in the last few years and the heat pumps we used continue to provide heating in -20 degree outside air.

The net result is that each building produces approximately 1,116 KWH annually more than they consume. These buildings are providing power to the grid far more than they use, which is the kind of good stewardship and citizenship that aligns with the WMSC mission.

The project was a success for the environment and the community. The buildings performed better than anticipated and allowed the Walking Mountains Science Center’s Pete and Pat Frechette Educator Housing to double educator staffing, increasing their service to the community by providing more natural science education.

“Although there was a premium to build net-zero homes,” the client tells us, “the operational expenses make it very affordable for us to provide the quality housing that we do. The other reason the housing is so successful is due to the architecture, the aesthetics, and the interior design.”

Brian Sipes is the Founding Principal for Sipes Architects, an architecture firm that designs authentic, sustainable, and modern residential and commercial projects in the mountains of Colorado and beyond. View their profile or contact Brian or Todd at 970.236.1519.

Content for this article is provided by Sipes Architects.