In Las Vegas, they are calling a monster home sustainable and green. In Denver, they are building a row of houses in response to the Denver Superefficient Housing Challenge.
These teams are tasked with designing five “demonstration homes” that are at least 50–60 percent more efficient than local building code and within the DHA’s affordable housing cost parameters. Meeting this efficiency goal could allow for a small solar array (say 200 to 400 square feet of panels) to fulfill the entire home’s energy demands. The challenge not only gives the Denver Housing Authority models to use for future buildings, but those models will actually be built and lived in, providing five Denver families with homes that are efficient, healthy, and affordable.
One of the winners was Toronto's Ryerson University with The Harvest Home. Like the house in Las Vegas, it is designed with the real estate development industry in mind, if a bit of a different market sector. From the press release:
“The idea of the Harvest Home was to design a highly insulated building that can exploit natural solar energy to create a comfortable and pleasant home that would be appropriate for a developer home,” says faculty supervisor Mark Gorgolewski. “We wanted to be able to harvest the natural resources made possible by cycles of nature.”
They expand on this in the brief:
To harvest in the traditional sense of the term refers to the gathering of agricultural crops - a collection of resources made possible by the cycles of nature. The Harvest Home expands this definition beyond the agricultural context through the exploitation of natural solar and precipitation cycles in pursuit of superior building performance made possible through passive, contextually informed architectural design. The 1,175 square foot, two and one half storey row house aims to become a cost effective, Passive House certified, net-zero energy ready model home. Through the development of an optimized building form, envelope and material palette, the home’s preliminary construction cost is projected to be approximately $182,000 or a modest $146 per square foot. In addition to its inexpensive construction, the Harvest Home promises a significant reduction in annual energy costs.
A tight, efficient plan with lots of natural lightIt is a straightforward plan, with an open concept floor to maximize penetration of natural light. In fact, it is pretty much a traditional Toronto side-stair Victorian house post renovation, although that would have three bedrooms instead of the third floor multifunction space. Perhaps it is convertible.
Built to Passivhaus principlesDesigning a row house is already more efficient in terms of energy because of the dramatic reduction in exposure. However when you build walls to R-43.5 and roof to R-55.6 and add in carefully placed, modestly sized high quality windows, carefully work to eliminate thermal bridges, and you get an energy-efficient package that has estimated electricity costs of $ 376 per year. Invest in a little bit of photovoltaics and you are net zero.
Employing Passive House principles to significantly reduce energy demand and heating loads, along with consideration for future photovoltaic installation, the Harvest Home is Net Zero Energy ready. Designed air-tight and thermal bridge free, the envelope provides excellent continuous insulation and appropriate moisture control. Glazing distribution and solar optimized pergolas take advantage of the abundant solar exposure and reduce over-heating.
There's not really a whole lot of high tech in this house; a pretty standard 12,000 BTU Mr. Slim minisplit heats and cools the whole thing. The ERV unit and fresh air makeup system mixes it all up for even heat distribution. There's a big GE heat pump water heater with preheat using a power pipe. Really simple stuff.
But because it is built to Passivhaus standards, the annual energy consumption and cost is negligible. Because there is so little gizmo green, the maintenance costs are similarly going to be tiny. It is just a great example of why Passivhaus is so smart and net-zero so silly; you don't need acres of solar panels and complicated buy-back arrangements and feed-in tarriffs, you just need a shitload of insulation, careful design and siting, and a couple of warm bodies.
Really, someone should tell the National Association of Homebuilders that this is the New American Home.
Ryerson’s team consists of graduate students Patrick Andres, Mathew Carlsson, Antonio Cunha, Mark Grimsrud, Denver Jeremyn, Mitchell May, Moe Otsubo, Matthew Suriano, Filip Tisler, Matthew Tokarik and German Vaisman, with faculty advisors Mark Gorgolewski, Paul Floerke, Miljana Horvat, Vincent Hui, Russell Richman and Vera Straka.
Lloyd Alter teaches sustainable design at Ryerson University School of Interior Design, which was not connected to this project.