“We're trying to make a 100 year old house, a passive house.”
David Claus and his family have lived in the same Prince George, BC house for 17 years. They love the neighbourhood, with its curving streets, character houses and mature trees. Their house overlooks a popular park and playground, and is also close to the library and community pool.
The house itself is great for their active lifestyle, a comfortable place to land after hitting the slopes or band practice. And David loves the features that come along with a century-old house. “The ceiling is quite high and the house still has a lot of original wood details,” he explains.
Unfortunately, a 100 year-old house is not the most affordable on energy costs. And energy is something David Claus cares a lot about.
As the University of Northern British Columbia’s first energy manager, he put in place programs and initiatives that have led to more than $5 million in energy savings. He also oversees the University’s award-winning bioenergy systems, which provide heat to the majority of campus buildings.
So, it was only a matter of time before David turned his attention wholeheartedly to making his well-loved family home as energy-efficient as possible.
In previous years, he took on basic projects: sealing out drafts, adding attic insulation, and upgrading to a high efficiency gas boiler for heat and hot water.
But in 2023, the Claus family started work on a massive retrofit. They decided to build an addition onto the house, providing the perfect opportunity to completely upgrade the building envelope of the existing to high-performance standards and match the addition. But David had questions: “What level of energy efficiency do we target and how do we get there? What’s even possible?” He landed on the decision to go as far as he could.
“Basically, we're trying to make a 100 year old house, a passive house,” David said. Passive House buildings are notable for their well-insulated building envelopes and consume up to 90% less energy for heating and cooling than conventional buildings.
Stripping down and rebuilding
David hired James Lambert of Lambert Built Ltd. to handle foundation, framing and roof work. When we visited the Claus house in late fall 2023, they had already completed the project of adding foundation insulation “to keep the basement warm.” This involved digging around the concrete foundation and lining it with foam insulation. “We've got eight inches of foam, it goes all the way down eight feet to the footings,” David explained.
Above grade, the Claus house was a striking sight—the stucco siding had been stripped off, laying bare the building’s exoskeleton—framing studs, old spun wood fibre insulation, lath and plaster. The beautifully aged wood plank sheathing was all ambers and chocolates. “It’s lovely planking—they don't make trees like this anymore!” David joked.
Unfortunately, the planks have a lot of air gaps, letting cold air through. So after removing the stucco, David wrapped the whole house in an air and vapour barrier. “That keeps the air in the house and it manages moisture in the walls.” It also provides a nice flat surface so they could line the walls with wood trusses (made with offcuts from a local wood truss manufacturer, by the way). Essentially, David was expanding the exterior of the wall outward, creating a new 10 inch deep hollow to be filled with cellulose insulation.
Really, it’s a straightforward process that reaps huge benefits. David estimates that stripping the stucco, insulating the envelope, and installing new triple-pane energy-efficient windows, will significantly boost the insulation and air-tightness of the home. Its performance is expected to exceed the requirements of a brand-new Step 5 house, which is the highest level of performance in the current BC Building Code. In fact, even though David is increasing the size of the home by 60%, the total energy consumption is anticipated to drop by 63%. When he does need heating or cooling, much of it will be supplied by a new, cold climate heat pump.
Energy to change
Claus is clearly excited when he talks about the renovation, which he started in the summer and is now dragging into a chilly Prince George fall and winter.
“We are still living here full time and it’s getting cold,” David said. “We’re a couple months away from finished. I'm hoping, though, that we’re only a couple of weeks away from increased comfort.”
Despite the threat of frigid times ahead, from talking to David, it’s clear he enjoys the thrill of taking on such a challenging project.
“When we were planning this project, one of the questions that came up from pretty much every builder that we talked to, was, why not just bulldoze the thing and start over?” David explained.
“Part of what made this retrofit work economically for us was that we were comfortable with most of the layout.” They didn’t want a whole new house and they didn’t even want to make major modifications. “Keeping the existing house mostly as it was meant we didn’t have to replace plumbing and electrical and flooring and all those things,” all of which adds up.
For David and his family, this retrofit made financial sense. But when it comes right down to it, it makes tons of emotional sense as well, investing in the home and neighbourhood that his family loves.
This exceptional retrofit project is profiled as part of CEA's efforts to increase understanding of high performance buildings among local government officials, builders, contractors, developers, and others involved with building, renovating, and marketing homes. These efforts included an October 2023 event in Prince George where David Claus presented his retrofit project to an audience learning about future-proofing new and existing cold climate homes. The event was presented by Building a Legacy North with financial support from BC Hydro.
Key Stats about the Claus Home
Configuration: Single family home with new addition under construction
Size: 2,050 ft2 existing home (addition 1,250 ft2)
Renovation Budget: $375,000 for renovation and addition
GHG Emissions: EnerGuide projects savings of up to 4.3 tonnes CO2 per year
Energy Efficiency: Projected reduction from 127 GJ to 61 GJ annual energy needs
Air tightness: Projected reduction from 6 to 0.6 air changes per hour
Climate Zone: 6
Insulation: Shredded fiberglass; no rigid insulation or spray foam used aside from under slab.
- R-38 basement foundation (EPS foam)
- R-44 exterior walls (mineral wool and cellulose)
- R-88 attic (cellulose)
Windows: Triple-glazed wood windows with aluminum exterior trim (Ug = 0.528 W/m²K)
Heating and Cooling:
- Midea Multi-split cold-climate heat pump for heating and cooling.
- Boiler provides back-up heat with hot water radiators.
Hot water: Viessmann Vitodens 100-A on-demand boiler (natural gas)
- High priority on material re-use – both from the existing house and from other construction/renovation projects.
- Adding Zehnder ComfoAir Q600 Energy Recovery Ventilator for ventilation.
Passive House: A voluntary energy-based standard for building design and construction. Passive House (Passivhaus) buildings consume up to 90 percent less heating and cooling energy than conventional buildings.
Net-Zero: A net-zero energy home produces as much energy as it consumes on a yearly basis and has at least one on-site renewable energy system.
Net-Zero Ready: A net-zero energy ready building has been designed and built to a level of performance such that it could, with the addition of solar panels or other renewable energy technologies, achieve net-zero energy performance. This is equivalent to Step 5 of the BC Energy Step Code.
Energy Step Code: The BC Energy Step Code sets performance requirements for new construction and groups them into Steps. Local governments can choose to require or incentivize a given step in new construction. Meeting Step 5 for homes is equivalent to building a net-zero energy ready building.
CEA supports the Building A Legacy North initiative, a collaboration with Canadian Home Builders Association (CHBA) of Northern BC. Learn how the initiative is encouraging the construction of more high performance buildings through implementation of the BC Energy Step Code and Zero Carbon Step Code in Northern BC.