With a heating bill of $77 CAD for an entire winter, the Naugler House is without a doubt the most energy-efficient home in New Brunswick. Not only will it save money long-term, it is saving money right now, as the monthly savings on utilities outweigh the added mortgage cost for energy-efficient upgrades to Passive House standards. This blows a gaping hole in the myth that high performance homes don't pay off.
As the owners, we enjoy the pleasant and spacious feel of the living space. Large windows on both levels not only provide free heat, but increase the spaciousness of the open design and provide natural light to the home for most of the day.
Moreover, the house has excellent indoor air quality, and is extremely quiet inside. Quality construction is required in order to meet the high standard for a Passive House including an airtight building structure, thick walls, solid windows and doors. This provides the house with a substantial cozy feeling and comfortable healthy living.
And, just to repeat, the $77 a year heating bill is hardly a heating bill at all for chilly New Brunswick.
During the planning period of the house we set out several goals:
- To build a certifiable Passive House
- To build the best house possible and use it to demonstrate the benefits of Passive House to Atlantic Canada
- To heat the house only through post-heating of the HRV fresh air
- To build the most airtight structure possible
- To use as many local, sustainable building products as possible.
Keeping to these goals helped in making all the hard decisions that come through the planning process.
Using the Passive House Planning Package [PHPP] software to ensure the home would achieve the Passive House Standard, we designed the envelope and chose our building materials carefully to provide a continuous layer of insulation and airtightness around the whole home. We ensured our construction methods were based upon sound building science.
Passive House open-concept design
Garth Hood of Thoughtful Dwellings in Fredericton helped to create this Passive House open-concept design. The living area is located to capture the view, with sleeping quarters and utilities located on the lower level. The design has the flexibility of accommodating large group gatherings, and with only minor renovations can be adapted to one-level living should that be needed in the future.
Garth, a certified Passive House Consultant, was an important part of the team that made the Naugler House a success. His design and energy-modelling skills aided to blend homeowner needs with the Passive House certification standard.
Passive House Construction:
The high level of insulation begins with the foundation, where 9’’ of type II and III expanded polystyrene [EPS] panel insulation placed below the slab was designed to also serve as the formwork. The outside of the concrete walls has 12’’ of type II EPS. The inside face of the foundation has an exposed plastered finish for additional thermal mass.
FPSF Frost Protected Shallow Foundation Perimeter skirt insulation detail
Above grade Passive House wall assembly:
- Locally-milled eastern white cedar clapboard siding and stained white cedar trim.
- Strapping for a 1.5’’ rainscreen
- 16’’ Larsen truss wall system clad with 1x8 board sheathing and filled with dense pack cellulose insulation, designed by Southern Exposure, provides a thermal bridge-free building envelope that is fast to assemble with minimal work on staging. It keeps the insulation in the same plane as the foundation insulation.
- Interior face of the Larsen truss wall finished with 7/16’’ oriented strand board [OSB] taped and primed with the OSB as the air and vapour barrier.
- 2x4 service cavity wall insulated with blown fiberglass with a binder, then completed with 1/2’’ drywall.
The roof covering is an 80%+ recycled composite polymer-based product that resembles slate tiles and is supported on trusses with a 32’’ raised heal and 30’’ of loose fill cellulose. Next comes a 6 mil polyethylene barrier sealed with tapes, then 1.5’’ strapping to create a service cavity, followed by 1/2’’ of drywall.
Dense packed cellulose insulation in the walls
Heating and ventilation:
With a PHPP calculated heating load of 7 W/m2, the heating requirements of the Naugler House could easily be met through the HRV ventilation system, eliminating the need and expense of installing a separate heating system.
A PH-certified Zehnder Comfoair 200 was chosen for the HRV, with a 92% heat-recovery rate. In the supply air from the HRV is a Thermolec 2000 Watt resistance heater unit which self-modulates the heat output. This unit provides all the heat needed to maintain the home comfortably at 20°C on a grey winters day.
Before outside air enters the HRV it is preheated or pre-cooled using a simple heat exchanger connected to a 325’ long ground loop of 3/4” pipe buried 5’ deep. Using a circulator pump and electronic control, fluid is pumped through the ground loop and heat exchanger to heat or cool the air entering the HRV.
In the winter when the air temperature outside is -25°C, fresh air is warmed to +2°C before it enters the HRV. This eliminates the need of using an electric heater to pre-warm the air. In the summer when the temperature outside is +33°C, fresh air enters the HRV at +22°C. The system was primarily designed by Garth Hood, using off-the-shelf locally-available materials.
Cost of Building this Passive House:
The 1,940 sq. ft. Naugler House, with a number of custom and durable building features beyond energy-efficiency upgrades, cost $150.00 per sq. ft. to construct. The increase in cost to achieve Passive House energy efficiency over Canadian Building Code energy efficiency was 15%. With similar custom features a code-built house in Fredericton would have cost $130.00 per sq. ft.
Operational costs for this Passive House design:
The Naugler House cost $2,140.82 less to heat per year than a house of the same design, on the same site, built to code. The $178.40 per month saved on heat more than pays the additional monthly mortgage payment of $152.00 to build to the Passive House standard. The above calculations do not take into account energy savings due to more efficient HRV.
The monthly cost of living in the Naugler House is less than living in a code-built house of the same size and design. This will be more the case when New Brunswick electricity rates increase 2% in October 2013. “Passive House provides energy stability, so there is no reason to not build a passive house,” conclude owners Janis and Win Naugler.
Win Naugler is the owner of the house and father of builder Tim Naugler of Southern Exposure Construction Inc.
- PHPP Specific Space heat demand = 7 kWh / [m2/a]
- PHPP Primary Energy Demand = 100 kWh / [m2/a]
- PHPP Heating Load = 7W / m2
- Airtightness = 0.2ACH@50Pa [European testing value] 0.18@5Pa [North American value]
[ACH stands for Air Changes per Hour. Pa stands for Pascals, measuring the pressure difference between inside and outside of the house. Testing is done at 50 Pascals to simulate wind pressure on the outside of the house. The R2000 standard for airtightness is 1.5ACH@50Pa. The Passive House standard is 0.6ACH@50Pa.]
- Treated floor area [TFA] = 161 m2
- Domestic hot water = two-panel flat-plate collector system
- Measured energy use June 14, 2012- June 12, 2013
- Energy used for heating = 690.2 kWh or 4.28 kWh / [m2/a]
- Total home energy consumption = 4,018 kWh or 24.95 kWh / [m2/a]
- Code-built total home energy consumption = 28,228 kWh or 175.3 kWh / [m2/a]
[Based on a Hot 2000 modelling software file for the same size, same design, same lot and orientation.]
- True-foam Type II and III expanded polystyrene, custom cut sub slab and exterior foundation insulation
- Blown cellulose insulation for walls and roof
- Air barrier: OSB with SIGA air barrier tapes
- Tyvek® water-resistive barrier in rain screen
- Passive House Windows: Internorm ThermoPassiv sourced through Northwin Windows
- Thermolec 2kw Thermo Air resistance heater unit
- Zehnder Comfoair 200 HRV
Naugler House annual heating cost [2012-2013]
- kWh used 690.2
- $/Month 6.40
- Total $ 76.82
Heating cost for the Naugler Passive House compared to code-built house:
- kWh 19,924
- $/Month 184.80
- Total $ 2,217.64
To see more articles about Passive House certification, design or construction see here, from the EcoHome Green Building Guides, on North America's favorite green building website - EcoHome.net...
|Finished Passive House standard home
This article was written by owners and builders Win and Tim Naugler, and first published by our print magazine partner EcoHouse Canada. All images are courtesy of Bang-on Photography. Visit the Naugler House website for up to date energy use information.