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Heat recovery ventilators: the shortest path to meeting new B.C. Building Code requirements

Image of cutaway illustration showing HRV system

'It seems HRVs are often installed as an afterthought'

When homes were leaky, planning for effective ventilation didn't matter so much. But the new B.C. Building Code increases the air tightness requirements for new homes in B.C., making ventilation increasingly important.

The Code also requires "balanced ventilation." While it doesn't specifically prescribe heat recovery ventilators (HRV), the balanced ventilation requirement certainly suggests their use.

For some builders, that may present a challenge.

"I would say most builders don't have any experience with HRVs," says Don Taylor of DW Energy Advisors Inc.

Taylor is a certified energy advisor who helps builders qualify for Power Smart incentives and EnerGuide labeling. He has tested numerous homes in the City of Vancouver, which has required HRV installation since 2008.

Poor HRV installation can eliminate benefits

"I've seen a lot of problems with HRV installation," says Taylor. "It seems they're often installed as an afterthought, because they're mandated — sort of, 'Oh no, I forgot the HRV.' So they put it in wherever it's easiest."

Taylor has seen HRVs installed in attics (the new Code will require HRVs to be inside the conditioned area of the house), without access to electricity, with the drain tube pointing upwards, and sealed inside a wall with no access for maintenance.

Installed correctly, HRVs improve both ventilation and energy efficiency. As stale air is exhausted, it passes through a heat exchanger so that fresh air entering the home is pre-warmed (or cooled, depending on the season). This reduces the load on the furnace (or air conditioner), while also ensuring adequate fresh air into the house.

When HRVs are improperly installed, however, they lose efficiency, and become a potential maintenance problem for the homeowner. But Taylor says they're the most straightforward way to meet Code requirements — and less challenging to install than some builders may realize.

HRV installation may cost less than work-around solutions

Taylor has heard builders discuss ways they plan to meet code requirements for balanced ventilation without using HRVs. But he's not convinced these ideas are in the best interest of the builder, or the buyer.

"Some have talked about multi-speed fans for the furnace, but that's not going to be cheap," he says. "Others plan to install bathroom exhaust fans that will run all the time. But that means exhausting conditioned air — so the heating system will likely run more frequently to make up for it.

"It's likely some builders will spend more money trying not to put an HRV in than they would if they just installed the HRV."

Taylor says he knows a number of custom builders who have easily incorporated HRVs into their designs. For those who haven't, investing some time into learning about the units — and into planning for their installation — can make all the difference.

"For example, the ducting that's required is less difficult to work with than some builders realize," he says. "And if you have a furnace, you can choose passive ducting, where the HRV makes use of the existing furnace ducts."

He points out that incentives help defray the unit's costs.

Efficiency and fresh air improve to the marketability of the home

Doug Overholt agrees that adopting HRVs makes sense. The program representative for the Power Smart New Home Program, he says an HRV is a great investment if you achieve a proper design and installation.

Overholt says that means understanding the basics:

  • Proper sizing
  • Locating the unit appropriately within the thermal envelope
  • Aair sealing the distribution system
  • Sloping drains for proper release of condensate
  • Allowing for seasonal removal and cleaning of the filters.

"They offer improved efficiency and superior ventilation, which adds to the comfort and marketability of the home," he says. "They're also the shortest path to meeting the new Code requirements. But they have to be installed properly; otherwise the HRV is just another energy consumer in the household."