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Case Study

A 100-year old Energy Star home

Location: Bozeman, MT

Leading green homebuilder in Bozeman, MT practices what he preaches with this gut rehab

Anders Lewendal likes to lead—he is President of his local homebuilder’s association and chairs its green building committee, sits on the Mayor’s Climate Control Task Force, and has had entries in the Bozeman Parade of Homes 7 of the last 10 years. So when he decided to remodel a 100-year old period home in Bozeman, MT, it had to be a gut rehab shooting for an Energy Star label. This is no mean feat—there are only a handful of these projects in the entire NorthWest.

A brief history of 711 North Black

This home started out as a farmhouse on the “edge of town” in the early 1900s. In 1972 the home was moved to 711 North Black, only 7 blocks from Bozeman’s downtown Main St. Another thing that Anders likes is to move; taking on the gut rehab of this 100-year old building as his own home meant moving for about the 25th time in just about as many years. But as Anders likes to say, “We learn a lot with each project, particularly if it’s our own home.”

As a rental property in 2002, Anders did some upgrading to the house: he replaced the windows, put on a new roof, added some insulation in the attic, put in a new furnace, resided and painted it. This meant that the gut rehab in 2008 completely focused on the home’s interior—it was gutted down to bare studs throughout and some interior walls moved to reconfigure spaces as well.

In 2008, a bit of serendipity led to the gut rehab of the main house at 711 North Black; Lewendal tenants were moving out and his family had just sold a large home. So Lewendal charged right in to turn the 100-year old farmhouse into their family home.

What green means to Anders Lewendal

Anders Lewendal did not get any sort of green certification for his project (although this is not to downplay the importance of the home being NorthWest Energy Star-certified). But he is pretty sure the project would do well. Lewendal takes a deep breath: “We started off with high density [3 dwelling units on just under 10,000 square feet or about 1/5 of an acre] near downtown, we reused the main house by gut rehabbing it, we super-insulated the main house, added a PV system, and salvaged what we could from the retrofit. That is green and sustainable in my book.”

Lewendal uses recycled content building materials as much as possible in his projects. The backyard fence proved to be an interesting project. “We used miscellaneous materials from our cabinet maker, trim supplier, and other subs. My wife randomly cut the pieces, handed them to me, and I blind-nailed them in to a fence. The result is eclectic and interesting; we get compliments all the time. Besides, it was cheaper than marriage counseling.”

Wrapping up, Lewendal said, "It's pretty expensive to gut a 100 year old home and bring it up to current energy standards. It is not for everyone, but we enjoy the location in town and the mature landscaping that comes with an older developed neighborhood."

Lessons Learned

Lewendal is unsure that the marginal energy savings of the full depth spray foam are worth the expense. “Our latest project will have 2 X 4 exterior walls filled with just 3 inches of closed-cell spray foam but have 2 inches of DOW blue board on the outside,” says Lewendal. “We will only do OSB for shear and end up with an R-31 wall without thermal bridging. We think that this will be a more cost efficient wall assembly for our climate.”

He would also like to have a better monitoring system for energy consumption and production in his homes. "Too bad we did not live in the house before the remodel so we can compare apples to apples on the energy consumption change [Lewendal tried several times to get pre-remodel energy consumption information, but it just was not possible]."

Lewendal has always wanted to do more recycling of construction waste and now they can. “We now have a local business grinding construction waste materials for about the same price as trucking and tipping at a landfill.” Another layer of green.

Lewendal’s company is using what it learned about green on this retrofit project to drive it’s next project: small, 960-square foot, modular homes with HERS scores of about 40 with renewables getting them to net zero (see last image in the photo gallery above). “If we can build these homes for under $200,000, everything included, we will be bringing really green homes to the market for everyone.” Keep your eye on the GBA Jobblog for this new project from Lewendal.

General Specs and Team

Location: Bozeman, MT

Bedrooms: 4

Bathrooms: 2.5
Living Space: 2200 sqf
Cost: $182/sqf

This square foot cost total includes exterior patios, paving, heated working garage, landscaping, and all permitting.

Construction: Anders Lewendal Construction, Inc.
Energy Star Verifier: Infrared USA
Heating: Radiant Engineering, Inc.
Ventilation: TinWorks, Inc.
Cabinetry: DC Monson


Basement insulation:2.5-in. EPS (R-10)

Wall construction:R-35 closed-cell spray foam cavity fill (existing 2 by 4 furred out to 2 by 6)

Windows:Energy Star builder-grade vinyl windows (U=.34)

Ceiling insulation:8 inches closed cell foam (R-56)

Roofing:25-year warranty asphalt shingles

Siding:Hardi-Plank fiber-cement lap siding


Heating Degree Days:8156

Cooling Degree Days:200

2009-2010 Total Household Energy Consumption:107 MMBtus

US EIA Average Household Energy Consumption (> 7,000 HDD):118 MMBtus

US EIA Average Household Energy Consumption (built before 1940):120 MMBtus

Boiler:95.2 AFUE Viessmann Vitodens 200 gas boiler

LED Lighting: LED-Eye Series Studio A American Fluorescent

  • Water Efficiency
  • Toilets: Sterling Dual-Flush
  • Clothes Washer: Maytag Performance Series (h-axis)
  • Indoor Air Quality
  • Lifebreath HRV
  • Green Materials and Resource Efficiency
  • All 1st floor fir flooring kept in place/refinished
  • 85% efficient gas furnace reused off site by HVAC contractor
  • Wool carpet salvaged from previous job change-order
  • Backyard fencing from cabinetry and trim millwork scrap, offcuts


NorthWest Energy Star

Image Credits: Marilyn De Kleer

Content By GBA
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