The Design Philosophy
The underlying goal of the Ecohome Demo House was to design a home that would greatly outperform conventionally built homes, yet be on par with those homes in construction cost.
By Mike Reynolds
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Heat retention before heat generation
Homeowners can have lower monthly costs when a construction budget is weighted towards reducing heat loss.
When a design team focuses on heat retention of a super-insulated home rather than heat generation, the net result can be a home that is cheaper to own operate from day one. Added building costs can be offset monthly by lower heating costs.
Durability strategies, beginning with an above ground slab-on-grade home and superior wall drying abilities means that this house will have a longer than average operational life. This will help balance the added ‘carbon’ investment in terms of the embodied energy of building materials.
Small is beautiful
The exterior footprint of 1,552 square feet is only 65% of the average size of new homes currently being built in Canada. The objective of the design was to show the functionality and appearance of abundant space while remaining well under average in size, thus driving down costs of the home both financially and environmentally.
Passive solar design
• Bedrooms, bathrooms and the mechanical room are concentrated more toward the north side of the home, with living areas and open space to the south. This configuration allows the exposed thermal mass of the concrete floor to work effectively with the solar gains from the abundant windows on the south facade.
• Though its value is not recognized in PHPP software [Passive House Planning Package], significant thermal mass within the building envelope [slab floor] stabilizes indoor temperatures at desired levels, leading to increased comfort and consequently energy savings.
• 60% of window and door openings face south for passive heat gains, where on a 24-hour cycle they end up providing a net heat gain in winter.
• Sun shades were designed into the south elevation, but with shading from deciduous trees they proved unnecessary.
• North-facing windows were included for day lighting and quality of life, but kept to a minimum to reduce heat loss.
• Integrate design features which allow for changes in layout with minimal cost and disruption.
• A bungalow on a slab-on-grade offers versatility to families of all ages [including the elderly with limited mobility]. All the doors and front access were planned to enable access to occupants with mobility issues.
• Floors will be finished before putting up divisions, enabling future changes to the layout without the costs and hassle of requiring flooring alterations.
• The floor plan was designed and the house positioned to allow for an addition if desired off the west living room wall.
• Storage was designed into the home, but the building was located on the lot to allow for a secondary building such as a workshop or storage shed to be built onsite within municipal bylaws.
Mike Reynolds is a former home builder, a LEED for Homes Green Rater, and the editor of Ecohome.net .