nnovative buildings The Luet House Living Off-grid in the North Carcross, Yukon

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1 i nnovative buildings The Luet House Living Off-grid in the North Carcross, Yukon When building a home in the north or in remote areas, utility-owned services and connections such as water and energy can be costly or simply not available. Alternative, renewable energy such as photovoltaics (PV), wind and wood can supply power and heat to a home, and minimize environmental impact. This case study examines an energy-efficient, off-grid* home in Northern Canada whose design optimization was explored during a design charrette sponsored by Natural Resources Canada (NRCan) in After having lived off-grid for 10 years, starting in a trailer with no electricity, no running water, and only a small woodstove, Trish and Joel Luet decided to design and build a new off-grid timber frame home in Carcross, Yukon. Over the years, the Luets' off-grid energy sources progressed from candles and propane lights to a small photovoltaic system with a back-up generator. When they began planning the * Homes without utility-supplied energy are known as off-grid.

2 construction of their new home for a three-acre (1.21 hectare) forested lot, they realized that living off-grid had become integral to their lifestyle, and chose to stay off-grid despite other energy options. The Luets wanted an energy-efficient house that minimized the impact on the environment by reducing the embodied energy used in its construction. Their timber frame building requires minimal work to maintain and manage. The house is solely powered by renewable energy for eight months of the year. Off-grid northern housing can greatly benefit from renewable energy sources. However, in order to optimize these resources, the optimal mix of renewable energy collectors such as PV, wind turbines and micro-hydro must be considered in conjunction with load management. To optimize, the energy that the household plans to use must be estimated and the energy sources sized accordingly. The larger the system, the more it will cost. In the North, the timing of optimal generation does not coincide with maximum energy need. For example, in summer when there can be 20 hours of usable solar radiation on a clear day, the electrical and heating loads are smallest. In winter the opposite is true, when there may be only one or two hours of solar input. The Luet's house was one of three northern homes addressed during a NRCan-sponsored integrated design charrette held in Whitehorse. The charrette focused on renewable energy use, overall energy efficiency of off-grid houses in the Yukon, and ways that all energy use could be reduced. Luet House was the most energy-efficient house of the three modelled in the design optimization process. The following provides the technical details of the house, followed with recommendations to increase energy efficiency further. 2

3 Highlights Completely powered by renewable energy for eight months of the year. 100% of electricity used from February through mid-november is supplied through a vertically mounted eight-panel, 680-watt photovoltaic array. A back-up gas-powered generator provides power for the remaining period. Renewable energy sources (wood and PV) supply per cent of the total annual fuel consumption. Energy consumed per volume of space is low at 3.0 kbtu/ft 3. (This was the lowest energy consumption of off-grid northern houses that were surveyed for NRCan in The 29 others' energy consumption ranged from 5.3 to 21.1 kbtu/ft 3, while the average was 9.0 kbtu/ft 3.) The Luets consider that there is little work required to maintain their energy systems except for maintainance of the battery banks. Building type: Single family, timber frame of two stories plus a loft, attached garage Status: Completed 2001 Construction cost: $165,000 to build and $15,000 for renewable energy system of wood plus PV, plus the sweat equity of owner/builders Owners: Joel and Trish Luet Site area: 3-acre (1.21 hectare) lot Gross floor area: m 2 with a heated building volume of m 2 and a footprint of 74.2 m 2. The envelope area is m 2. The space is based on an open concept plan. Number of occupants: 2 House Design: Trish and Joel Luet Solar system: Kris Selzer of Solar 2 (Whitehorse, Yukon) Structural: Wayne Wilkinson (Whitehorse) assisted in the design of the Larsen trusses for the walls and roofs. Timber frame design: Thistlewood (Ontario), in collaboration with the Luets Material: locally grown and milled timber Generation System Summary PV Renewable Energy: 8-panel array generating kw Generator Set: 3.5 kw Total Capacity: 4.1 kw of which 14.6% is renewable energy Total Daily Summer Load: 4.37 kwh Total Daily Winter Load: 8.35 More details can be obtained on the Canada-Yukon Energy Solutions Centre website at 3

4 Other vital information: Thermal envelope: The building had high insulation levels, blown cellulose to R45 in the ceiling (R59 over the loft), and a combination of blown cellulose and fibreglass to R38 in the walls. The fibreglass insulation had 40 per cent recycled glass content. Window characteristics need to be carefully selected in off-grid housing. The Luets chose high-efficiency triple-glazed units with hard coat low-e, with insulating spacers and a half-inch argon-filled space. There are only two small windows on the north side of the building. Another important aspect of the design is its high air tightness at 1.47 Air Changes per hour. The whole envelope leakage area is cm 2 The rectangular building footprint maximizes southerly exposure for passive solar heating and allows the low winter sun to penetrate to the back wall of house. The post-and-beam construction used locally grown and milled timbers. Roof and walls constructed with Larsen trusses using 50 per cent less wood than standard wood-frame construction significantly reduced thermal bridging. 4

5 The energy generated by the 680-watt photovoltaic array is stored in a battery bank of six, two-volt, Surrette batteries with a capacity of 1,575 amp hours. A Trace SW2512 inverter converts the stored electricity into 120 volt household power. Interior lighting consists of high-efficiency, compact florescent. Three low- voltage lights are used outdoors. The primary heat source is locally harvested wood burned in a Tulikivi soapstone mass masonry heater. This highly efficient wood burner uses 50 per cent less wood and burns cleaner than conventional wood stoves. Most of the wood is from construction site scraps, little is harvested from the poplar forest on the property. Backup heat is provided by a Rinnai directvent propane space heater. The roof surface is metal, chosen for ease of installation, durability, fire resistance and ability to be recycled. Cooking is done on a wood cookstove that provides additional space heating. A propane two-burner cook top is used for smaller cooking jobs. Water heating is provided by a Bosch on-demand propane water heater that is 30 per cent more efficient than conventional hot water heaters. Potential for Improvement: A team assessed the potential for the use of a greater proportion of renewables for this home at a design charrette sponsored by NRCan in collaboration with Yukon Energy Solutions Centre. 1 Efficiency and comfort could be improved in future designs by actions that for the most part would have a payback of five years or less. These measures include: better insulation to reduce wood use by five per cent thermal separation of the ground floor living space from the non-living spaces such as the garage 5

6 better sizing of the generator to fit the loads increased use of electrical appliances in summer, such as switching to an electric refrigerator instead of the current propane one to take advantage of excess solar capacity. Double PV storage capacity to offset this change. These changes could increase the renewable energy use to 76.5 per cent of the total energy required. An extra $6,000 would cover these changes and provide a payback of five years and less as energy costs escalate. Presently the homeowners are installing a warm-air return system to redistribute the warm air from the upper level ceiling down to the ground floor. 1. Living Off-Grid on Renewable Energy in the Yukon, J. Ayoub, S. Henderson, R. Alward, R. Sheriff, NRCan, SESCI 2004 Conference paper, Waterloo Ontario 2. CMHC About Your House - Photovoltaics (PVs) 3. CMHC About Your House - Backup Power for Your Home 4. CMHC About Your House - Your Septic System 2005, Canada Mortgage and Housing Corporation Printed in Canada Produced by CMHC If you have any comments, or would like to submit your project for publication, please contact: smarshal@cmhc.ca For more information about innovative building solutions and green buildings, visit Canada Mortgage and Housing Corporation (CMHC) website at OUR WEBSITE ADDRESS: Although this information product reflects housing experts current knowledge, it is provided for general information purposes only. Any reliance or action taken based on the information, materials and techniques described are the responsibility of the user. Readers are advised to consult appropriate professional resources to determine what is safe and suitable in their particular case. Canada Mortgage and Housing Corporation assumes no responsibility for any consequence arising from use of the information, materials and techniques described. 6