Single Family Passive House, Okatoks, Alberta

Project Overview

This project is expected to be the first Certified Passive House in this region, and it started out with a primary requirement for a healthy building by the owners – a young Alberta family who are very aware of and cautious about toxicity in common building materials. Distance from power lines made it a simple decision to go off-grid right from the start, and this drove the requirement for extremely high energy efficiency in the building shell, so it only made sense to build all the way to the Passive House Standard. The building is located in the Alberta prairies South of Calgary with a spectacular view of the Rocky Mountains to the West. Capturing that view required larger windows on the west side than found in most Passive Houses, but significant overhangs and deep window reveals reduce the risk of summer overheating via these windows.

The house has a useable floor area (TFA) of 1776 sft, 4 bedrooms, an attractive open-plan layout on the main floor and a small meditation room. It also has an insulated attached garage/workshop. The building is wrapped with a porch roof for protection and summer shading. The building shell is entirely made out of sustainably sourced wood products – CLT and wood fibre board. The CLT functions as structure, vapor retarder, airtight layer, electrical layer and finish layer (it was ordered as finish grade) in one. The complete building and garage structure was assembled by the owners themselves in about 5 days. The building is powered entirely with PV panels and incorporates a rainwater collection system.

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Annual Heating Cost

$153 / yr*

* 1905 kWh heating energy per year, would cost 8 cents/kWh local rate BUT this house is off grid, so power is generated on site via PV/solar thermal at no fuel cost

See Building Performance Data

Building Performance Data (via PHPP modeling)  
Gross Floor Area 1880 ft2
Treated Floor Area (TFA) 165 m2 (1776 ft2)
Specific Annual Heating Demand 12 kWh/m2
Annual Heating demand 1905 kWh / year
Annual Heating cost $152 / year - grid electricity
Design Heating Load 2877 Watts
Specific Heating Load 17.4 W/m2
Target Airtightness 0.4 ach @ 50 Pa
Airtightness achieved under construction
Annual cooling cost zero

See Construction Details

Building Details Construction Type U-value (R-value) Manufacturer, Location
Floor slab Superinsulated EPS tray slab 0.13 W/m2K (R-43) Plasti-Fab, Calgary AB
Wall structure Cross-Laminated timber 0.13 W/m2K (R-43) Merk Timber, Germany
Roof structure Cross-Laminated timber 0.12 W/m2K (R-46) Merk Timber, Germany
Wall insulation Wood fibre board 280mm Schneiderholz, Germany
Roof Insulation Wood fibre board 280mm Schneiderholz, Germany
Window type Optiwin Resista (Passive House Certified 2015) Optiwin, Austria
Window Frame Fir / Thermally treated spruce 0.72 W/m2K Optiwin, Austria
Window Glazing Saint Gobain triple low-e/argon 0.5 and 0.6 (south) W/m2K Saint Gobain
Airtightness goal : 0.4 ach @ 50 Pa
Ventilation system Zehnder 350 90% efficiency Zehnder
Heating System Wood-Solar thermal

See Design & Construction Team

Architect Tomaz Stich, Stich Passive Design Invermere BC
3-D Modeling + CLT structure Tomaz Stich, Stich Passive Design Invermere BC
Passive House Designer Tomaz Stich, Stich Passive Design Invermere BC
Construction / Owners Scott & Sherri Daley Okatoks, AB
PHI-Accredited Certifier EZA! Kempten, Germany