Living Off-Grid in the City


Written by Wendy Priesnitz

One of the winners of Canada Mortgage and Housing Corporation’s (CMHC) Healthy Housing Design Competition, the Healthy House in Toronto, Ontario has been designed to rely on sun and precipitation as the basis of its heating, electrical, water and waste water management systems.

Healthy House Competition

In June 1991, CMHC announced its Healthy Housing Design Competition. The objective was to demonstrate to the public and the housing industry that it is now possible to design houses for the Canadian climate that are in keeping with the principles of sustainable development and are healthy for the occupants.

The competition challenged the industry to develop innovative ways to design homes with the right balance of occupant health, energy efficiency, resource efficiency, environmental responsibility and affordability. In February 1992, an independent jury selected two winners, one in Vancouver and one in Toronto. The Toronto winning entry is a 1,700 square foot semi-detached house on a vacant (infill) lot in an older part of the city known as Riverdale.

To demonstrate the independence of this Healthy House from conventional heating, water and hydro services, CMHC is paying $70,000 for some of the incremental costs of materials and systems that are not standard, and $13,500 for the project management and carrying costs during the six-month demonstration stage required by CMHC.

Martin Liefhebber of Martin Liefhebber Architect Incorporated designed the house, including the envelope and the passive solar heating and cooling system. Rolf Paloheimo, owner of Creative Communities Research Inc., a home building company, purchased the land and built the house. The major partners in this project are CMHC, The City of Toronto Public Health, Ontario Ministry of Health, Ontario Ministry of Environment and Energy, Ontario Hydro?s Environment and Sustainable Development Division and Toronto Hydro.

More than 80 companies have donated time and materials to the project.  House design, landscaping and technology are all used to help heat and cool the house and reduce dependence on the earth’s resources. Large, energy-efficient, south-facing windows and solar panels capture sunlight, while the thermal mass of the house (concrete floors and walls) make efficient use of solar energy.

The house uses about one-tenth of the amount of energy needed to heat a conventional house and the heating bill is estimated at $80 per year. This means that sunlight can provide most of the energy for space heating needs. Trees and ivy trellises provide shade in summer and do not block sunlight during winter.

The triple-glazed, thermally efficient windows are strategically located to make maximum use of solar gain and minimize heat loss in winter. Solar radiant floors have been specifically designed to retain solar heat during the day and radiate it to the interior at night. Heat radiates not only from floors, but from ceilings. Sunlight is collected through solar panels and heat is retained. If required, water warmed by the sun is circulated through pipes in the floors to supplement direct solar heat.

In summer, heat gain is controlled by window shading and moderated air flow. Efficient electrical appliances and grey water heat exchangers provide less internal heat gain and less need for air conditioning. Excess heat is radiated to the ground surrounding the house. In addition, the waste water system provides evaporative cooling through a heat exchanger. Energy storage and conversion technology ensures that the solar energy is available in whatever form is needed year-round.

When additional energy is needed, a co-generation unit supplies additional electricity and heat. The ventilation system is designed to ensure that the air entering the house is as clean as possible and is evenly distributed. Rain and snow collected from the roof provides all of the water supply. Water is stored in an underground cistern and purified without the use of chemicals.

The house is also water self-sufficient, depending on rainfall for its water supply. Rainwater is collected, filtered, purified and stored for drinking and washing. It is then recycled for use in the showers, washing machine or toilets. Water consumption will be approximately 120 litres per day for a family of three. Normal consumption for a family of three is 1,050 litres, or 350 litres per person per day.

The cistern, which contains limestone, gives the water a fresh taste and lowers acidity. Water then passes through a slow sand filter, just as rain water passes through the soil along to a river or stream. It then contacts activated charcoal to absorb any inorganic compounds. As a final precaution, ultraviolet light shines through the pure water to disinfect it without chemicals. No chlorine, aluminum or other additives are used to make the water safe to drink.

All of the waste water in the house is treated and purified. There are several steps in the treatment process. First, anaerobic organisms break down complex molecules into simpler compounds. A biofilter, using aerobic organisms, then devours and digests the waste, leaving nearly pure water. Following digestion, water passes through a slow sand filter and a carbon filter. Ultraviolet light shines through it for safety precautions. The result is clean, pure water suitable for uses in the house, such as flushing toilets and washing clothes. Surplus clean water that is generated filters into the ground under the front lawn, where it waters fruit trees and flowers.

In addition, the house features appliances, fixtures and devices that use less water.

Building materials/landscaping

The Toronto Healthy House is built and furnished with materials that emit fewer harmful vapours. Wood, paint, wallboard and fabrics have all been selected with air quality and overall energy and environmental costs in mind. Special blocks made of a lightweight but durable wood particle concrete, reinforced with steel bars, provide a structural wall system that increases the insulation level.

The blocks consist of 78 percent recycled natural raw materials.The low-maintenance landscaping is functional and aesthetically pleasing. The front yard features flowering perennials and edible plants. The back yard, which features two patios designed to collect surface water and divert it into the cistern, is quite dry and shady. Therefore, the ground cover and other plants for this area were chosen for their ability to thrive under these conditions.

Creating Your Own Healthy Home

Here are some tips from the Healthy Home project to make your living space friendlier to the environment and your health.

The Kitchen

Restricted Flow Taps: A simple and inexpensive aerator tap can reduce water use by more than 60 per cent.

Skylights: A properly designed skylight reduces the need for artificial light and saves on lighting costs.

Energy-efficient Appliances: Energy-efficient dishwashers, washers and dryers, refrigerators and freezers can cut energy consumption by at least 15 per cent. Some models can reduce energy use by nearly 50 per cent.

Waste Reduction and Recycling

Use bins to collect recyclable materials and to separate wet and dry waste.

Use a covered compost bin to store organic waste for composting outside.

Storage: Store materials whose odours can reduce air quality ? cleaners, toiletries, compost and garbage ? in a cabinet exhausted to the outside.

Cabinets: In the Healthy House, hardwood is preferable to particle boards, plastic laminates and other synthetic materials commonly used in kitchen cabinets. Domestic hardwoods, such as maple, are fast-growing and durable. Most important, they emit fewer vapours into the indoor air.

Plaster walls are attractive, durable, cleanable and inert.

For countertops, stoneware tile set in mortar is easy to maintain and durable. It consists of 70 per cent recycled glass.

Construction Practices

Dyed and Waxed Concrete Slab Floor: A low-emission water-based wax provides a low maintenance finish while eliminating concrete dust.

Rigid Board Insulation: Placed under the concrete slab, this high-performance, waterproof insulation helps raise the temperature of the floor slab and increases comfort.It loses as much as 75 per cent less heat through the slab than conventional construction.

Kiln-dried, Finger-jointed Spruce Studs: Spruce is a domestic, fast-growing and renewable softwood. It also has the lowest chemical content of the softwoods, so it improves the quality of the indoor air. Finger joints connect short sections of lumber, reducing mill waste.

Birch Trim and Molding: Birch, a fast-growing domestic hardwood, emits few chemicals and is very durable. It is an excellent choice for decorative trim and molding when sealed with a water-based dispersion urethane, a low-odour finish.

Fibre-reinforced Drywall: This gypsum drywall minimizes taping, filling and sanding. It contains recycled material and creates less dust and volatile chemicals during installation.

The Mechanical Room Fresh Air System: A fresh air system draws fresh, filtered air into the home while removing stale indoor air and odours. The air handler uses a variety of filters. Together, the fresh air system and associated heat recovery ventilator provide a healthier, more comfortable home.

Exercise care when designing and locating ventilation intakes and exhausts. Ventilation and furnace exhaust must not re-enter the house.

Heat Recovery Ventilator: This device regulates indoor air quality and the house’s indoor climate. It can recover 70 per cent of the heat from stale indoor air while providing a continuous supply of fresh air to the home. It reduces heat and ventilation costs.

Ducting: To ensure the efficient supply and return of ventilated air, ductwork must be airtight, yet accessible for cleaning.

Water Filtration: A water purification system for the whole house is more efficient in filtering out chemicals, bacteria and odours than small tap units.

Central Vacuum: A central vacuum system should have its motor and exhaust set outside the house, so it removes dust directly to the outdoors. This eliminates the kicked-up dust common to conventional vacuum cleaners.

Contact: Canadian Housing Information Centre 700 Montreal Rd.Ottawa ON K1A 0P7 Canada
Copyright permission given to bagelhole

Originally posted @ Sharing Sustainable Solutions


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