Image Credit: c. 2010 James F. Wilson/courtesy Builder magazine (images 1 and 2), KB Home (all other images)
Image Credit: c. 2010 James F. Wilson/courtesy Builder magazine (images 1 and 2), KB Home (all other images) The KB Home GreenHouse has 2,700 sq. ft. of interior space and, like many homes in Florida, a large covered patio. A rainwater catchment system helps irrigate the landscape, which includes elevated vegetable and herb beds. As is common for homes in Florida, the exterior walls were constructed of concrete blocks. The interior surfaces of the walls were later insulated with foam panels. KB Home used factory-built roof trusses to keep costs down. The interior of the roof system was sprayed with open-cell foam. Housewrap was applied to the exterior walls. The house is equipped with photovoltaic roof tiles and a solar hot-water system.
More Green Building News
The official unveiling this week of the KB Home GreenHouse: An Idea Home Created with Martha Stewart was preceded by a months-long drumroll touting its virtues: energy-efficient yet affordable, and, of course, representative of Stewart’s notions of comfort and style.
Judging from the photos of the 2,700-sq.-ft. house — which opened for tours on Wednesday to participants at the International Builders’ Show in Orlando, Florida — it does seem to deliver solidly on the traditional, Stewart-inspired styling and amenities found in many communities built by KB Home, which has had a marketing alliance with Stewart for some years. But the advertised energy efficiency of the house — net zero energy — is new to KB Home, which, along with Pulte Homes, topped a recent survey by Calvert Investments, a specialist in socially responsible investing, intended to rank the green practices of the nation’s 10 biggest publicly traded home builders.
Adding insulation, increasing airtightness
The thirteenth project in Builder Magazine’s Concept Home series, KB Home GreenHouse started attracting media attention last fall, while construction was still underway. KB combined the production-home strategies it uses to help control costs with techniques to increase the thermal resistance and airtightness of the concrete-block exterior walls and the roof, which includes a mix of concrete tile and, in some sections, photovoltaic tiles, plus a solar thermal system.
The interior surfaces of the CMU walls were insulated with foam panels. The exterior surfaces were covered with housewrap and topped with fiber cement siding. The roof was insulated with open-cell foam. According to Concept Home videos about the project, the home’s HVAC system includes a heat-recovery ventilator as well as a highly efficient dehumidification system. GreenHouse is located in Windermere, not far from Orlando, which sees very mild winters, comfortably warm weather in the spring and most of the fall, and hot semi-tropical summers.
As the first net-zero-energy home in the KB lineup — and as the main showcase for this product line — the company designed and built the house to qualify for a number of green-home credentials, including the Environmental Protection Agency’s Energy Star and WaterSense labels, a LEED for Homes Platinum rating, and an Environments for Living green certification.
Of the home’s $380,000 listing price, a premium of about $70,000 was spent to achieve net-zero-energy performance and the green-home labels mentioned above. A KB official noted that the price premium will shrink significantly as the company’s NZE category grows.
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6 Comments
Lloyd Alter's take
On the Treehugger site, Lloyd Alter explains why this house makes him cringe:
http://www.treehugger.com/files/2011/01/builder-concept-home-2011.php
Net Zero
This is an improvement on some of the earlier net-zero efforts, $140 per sf is reasonable. The fact production home builders are getting greener should be cause for celebration, they build the vast majority of US homes. I would like to see some listed R-values and other performance specifications.
Quality vs. quantity
Yeah, production operations have a knack for skewing the numbers in their favor
2,700 sq ft? Seriously? Why
2,700 sq ft? Seriously? Why so large? This is exactly the problem with new construction---we don't need to participate in the 'bigger, faster, more" mentality if we want to maintain affordable net-zero homes! I would argue that the price-point is WAY too high in the current market (even around Orlando!). If something similar could be built for ~$200k at ~2000sq ft. I think it would be relatively easy to scale this up to larger developments.
Focus
I like the jane jacobs stuff as much as the next reader, but let's be fair, KB is promoting a zero energy house not a zero energy development. Judge it on that. They're also in the business of selling homes. I cringe seeing a photo of a side-by-side refrigerator in the house's kitchen. I am angry seeing a monster of inefficiency 8.57 kW of solar panel tiles in the roof and I hate seeing cars with nicer roofs over their heads than most of the world's human population, but, hey, it's a start. Horton? Lennar? Hello? Where are they?
One other thing. I can't let your remark about cross ventilation go by without remarking HUH???? The house has an HRV. If that doesn't explain it, maybe you should be writing for House Beautiful.
Response to Barry
Barry,
What remark on cross ventilation? I can't find the remark you are talking about.
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