SABMag on high-performance housing: MAFCOHOUSE
Modernist, modular design comes to cottage country
Picture a mid 20th century Case Study house overlooking Los Angeles; the flat roof and glass walls, the refinement of form and Modernist ideals. Now transpose those forms and philosophies into the 21st Century amid the lakes and forests of the Canadian Shield in Haliburton, Ontario. MAFCOHOUSE is a contemporary building system that harks back to the architecture of Richard Neutra and Pierre Koenig but which also meets the environmental aspirations of today’s clients and building codes.
By Will Jones
Conceived by Dan and Diane Molenaar, the MAFCO concept was born in 2004 when an opportunity to reuse curtain wall glazing from a refurbished office tower in Toronto set the couple on a journey to build their own off-grid contemporary cottage on a bluff overlooking Drag Lake in Haliburton County.
“We designed a pavilion-like building around these glazed units,” says Dan Molenaar. “Their pivotal role in the design established the 16-foot [4.8m] structural grid and modular post and beam construction that has become the basis of all MAFCO houses.”
Today, MAFCOHOUSE has refined the design of its homes to take into account the most important criteria of environmental design. From the initial site visit and topographical survey, each house is designed to best suit its immediate surroundings and integrate with the unique characteristics of the site.
“The 16-foot [4.8m] module means that we can effectively juggle boxes to see how they will best fit into a site, with the least disruption,” says Molenaar. “Taking into account orientation to the sun, topography and required setbacks from water bodies, we design a one-or two-storey building that sits lightly within the landscape.”
The houses are positioned to take advantage of the property’s inherent features and to minimize activities such as blasting. Their flat roofs, glazed walls and cantilevered ground floor perimeter walkway reduces visual impact and they seem to almost float above the earth.
Large 12-inch [305mm] deep Parallam beams, supported by posts set at 16-feet [4.8m] intervals are the backbone of the MAFCO design. The stability of the structure is assured by structural engineer, Blackwell, using a series of diaphragm walls and hold-down connectors anchoring the post and beams superstructure to heavy laminated veneer lumber [LVL] floor beam to prevent racking.
This starting grid of industry-standard size ensures that materials are available off-the-shelf and used with the minimum of waste. The hard coat, triple-glazed walls, the inspiration for this house design, are typically 8-feet [2.4m] high and manufactured by Inline Fiberglass.
The flat roof features cantilevered eaves that overhang 4-feet [1.2m], shading the interior from the high summer sun but allowing the light and warmth of winter sunshine to penetrate almost 16 feet [4.8m]. Passive measures such as this are important to a design that can feature 40% to 50% glazed walls.
Blown-in-blanket [BIB] Insulation guarantees that non-glazed walls achieve R-32 and roofs achieve R-50; while concrete basements and crawl spaces are externally insulated with rigid foam. MAFCO has developed these and many more best practice criteria in conjunction with consultants Building Knowledge Canada and Building Science Consultants Inc.
The heating system within MAFCO houses plays a pivotal role in energy reduction. Most commonly, a geo-exchange combined heating/cooling system is installed, utilizing a lake loop. Aaron Tomlinson, of Tomlinson Mechanical & Geothermal, explains that geo-exchange is typically the primary heat source, often backed up by a high-efficiency wood stove.
“Radiant floor or forced-air systems operate using heat generated via the lake loop and heat exchange system; even waste heat from grey water is captured and reused, too,” he says.
The geo-exchange system strips an average of 5oF [2.8oC] from the lake loop, and, through a two-stage compression process, heats water in a radiant floor to 110 to 115oF [37.5-45oC], or forced air to 100oF [37.5oC]. During normal use, the electric coil within the water tank is not required. However, it kicks in during power outages if a back-up generator is installed.
The combination of passive measures and the geothermal heating system enable the MAFCO houses to meet the Ontario Building Code’s supplementary standard SB-12.
With minimal removal of organic matter from site, materials manufactured to exact size, super-efficient heating/cooling systems, quick, clean construction methods and standardized 16-feet modular design, MAFCOHOUSE could become a case study for a new generation of environmentally responsible houses in Canada’s cottage country.
Structural Engineer Blackwell
Mechanical Engineer Tomlinson Mechanical & Geothermal
Building Envelope Building Knowledge Canada and Building Science Consultants Inc
Will Jones is an architectural journalist based in Halliburton, Ontario.