SIPs Goes Mainstream Green

The Bunker Residence’s sustainable assets are found above and below ground.

When it comes to the Bunker Residence—Green Builder’s 2022 Green Home of the Year in the Mainstream Green category—environmentally friendly construction boils down to three letters: SIP.

The stylish, 3,120-square-foot single-family home in Tofte, Minnesota, was constructed on Lake Superior’s often-windy northern shore. This made it essential that the house have an airtight envelope and exceptional insulation to help make it as energy efficient as possible, according to Anton Moody, owner of Taiga Design+Build in nearby Grand Marais, Minnesota. 

Moody’s choice was clear: He used structural insulated panels (SIPs), a product that he has worked with many times. “[Anton] finds the pre-engineering, ease and speed of installation and air tightness superior to conventional framing,” notes Lee Bergum, district sales manager for Energy Panel Structures, the manufacturer of the SIPs used during construction. “SIPs save time and labor costs. The roof panels enabled this project to get closed in faster, using less energy expense during build.”

The designer/builder used 6-inch Neopor R-30 walls and 10-inch Neopor R-50 panels for the roof. The SIPs helped the Bunker Residence to an estimated Home Energy Rating System (HERS) Index of 28 and a blower door test result of 0.89 air changes per hour (ACH). 

Getting Warmer

The home also features dual-fuel, in-floor, radiant heat. The primary heat source for the hydronic fluid is an interruptible Slant/Fin Monitron electric boiler with 100 percent efficiency. The secondary source is a Navien propane boiler with 95 percent efficiency, which also serves as a secondary source of domestic hot water. 

An EcoTech air exchanger provides outside air. Loewen windows (with 0.27 U-Factor) and doors throughout, total LED lighting, and low-volatile organic compound (VOC) paints complete the overall green construction end of the project.

The house offers expansive views of the lake in all directions. Large southern windows allow for natural heating in the winter, while large shade trees provide extra cooling during summer.

“The clients wanted us to build a piece of art they could live in, while remaining true to our standard of energy efficiency and quality materials,” Moody says. “It was a fun back and forth between us as we found opportunities to create spaces they desired.”

Such opportunities included reclaiming the old foundation as a place where the owners could house their wine collection and share their passion for wine. There are also large exterior glulam beams for aesthetics and a walkout deck over the kitchen that allows for entertaining. “The view is breathtaking,” Bergum notes. “The home is very efficient, quiet, and withstands the harsh winds of Lake Superior. This was a fun project.”