Is an HRV Required in Nova Scotia? What the Building Code Actually Says

Search this question and you'll get four answers. A competitor's page says an HRV is required in most new builds and major renovations. A contractor on Reddit told a homeowner that Nova Scotia's code doesn't allow ERVs. Google's AI Overview mixes the two. And a good share of the province's tradespeople will tell you "it's code" without saying which part.

We read the code. Here is what it actually says, clause by clause, for a new house, a renovation, a basement suite and the older house most of Halifax lives in. Where the answer turns on something we couldn't read ourselves, we say so.

The short answer

The National Building Code of Canada 2020 is the code Nova Scotia adopted from 1 April 2025. It treats ventilation and HRVs as two different things:

• Ventilation is required in every new home with electricity and a heating system.
• An HRV is one way to provide it. It becomes required by name in one specific situation, explained below.

The rest of this page shows where each line comes from.

What every new home must have: mechanical ventilation

The requirement starts in Article 9.32.1.2. Every residential occupancy must have provisions for ventilation, and if it is "supplied with electrical power and a heating system," that includes heating-season ventilation. For a self-contained system serving one dwelling, the rules are in Subsection 9.32.3.

That subsection gives three ways to comply (9.32.3.1.(1)):

1. Good practice such as CSA F326, the national standard for residential mechanical ventilation systems;
2. The code's own prescriptive rules, for homes with five or fewer bedrooms; or
3. Part 6, the engineered route used for larger buildings.

Most houses use the second. It requires three components (9.32.3.1.(2)): a principal ventilation system, supplemental exhaust fans in the kitchen and bathrooms, and protection against depressurization where the house has fuel-fired appliances that aren't direct-vented.

Here is the sentence that settles most arguments. The principal ventilation fan, the one that runs to keep the house ventilated, "may be satisfied by a single fan, by the exhaust side of a heat recovery ventilator, or by a group of fans" (9.32.3.3.(3)). The HRV is on that list. It is not the list.

The principal fan has to move a set amount of air, based on bedrooms (Table 9.32.3.3.):

It also has to bring in outdoor air, either through the furnace's return ductwork (9.32.3.4.) or through a separate supply fan and ductwork to each bedroom and to any storey without one (9.32.3.5.). It needs a manual switch in the living area marked "VENTILATION FAN" (9.32.3.3.(5)). An HRV does all of that in one box: it exhausts the stale air, supplies the fresh air, and warms the incoming air with the heat of the outgoing air. That is why builders reach for it. But a principal exhaust fan paired with a properly ducted fresh-air supply meets the same section.

Where an HRV stops being optional: the energy rules

The ventilation section (9.32) is about health and safety. The energy section (9.36) is about heat loss, and that's where the HRV picks up weight. The code's own note says the two should be read together: 9.32 "addresses the effectiveness of mechanical ventilation systems … from a health and safety perspective," and 9.36 "is concerned with their functioning from an energy efficiency perspective" (Note A-9.36.3.9.(1)).

The baseline: an HRV buys you thinner walls

Under the baseline energy rules, walls, ceilings and floors must meet minimum insulation values from one of two tables: Table 9.36.2.6.-A "where the ventilation system does not include heat-recovery equipment," or Table 9.36.2.6.-B where it does. The code's note explains that the two reach the same energy performance by different routes, and that running an HRV "affords a reduction in the RSI values for some assemblies, most notably for walls and rim joists." An HRV isn't required here, but it changes what the rest of the house has to be.

The tiers, and Nova Scotia's schedule

The 2020 code added energy performance tiers, from Tier 1 (the baseline) upward. The province's announcement set out when each one applies here:

• Tier 1, building and energy codes: 1 April 2025
• Tier 2, national building code: 1 April 2026
• Tier 3, national building code: 1 April 2027

We read that schedule in the provincial news release, not in the regulation itself, which we couldn't open. Your building official can confirm which tier applies to your permit date.

A house can reach a tier above the baseline in two ways, and the HRV question depends on which one your designer uses.

1. The prescriptive points path (9.36.8.). The builder picks from a menu of upgrades, each worth energy-conservation points, until the house reaches the points needed for the tier. On this path the code is direct: "Ventilation systems serving buildings to which this Subsection applies shall be equipped with a heat-recovery ventilator conforming to Article 9.36.3.9." (9.36.8.9.(3)). That's the one place the code names an HRV as required for a house. In the national code text, this path only goes as far as Tier 2; the table lists the higher tiers as "Reserved".

2. The performance path (9.36.7.). The designer models the house's energy use against a reference house built to the baseline. An HRV isn't mandatory here. But the modelling rules say the reference house "shall be modeled without a heat-recovery ventilator" (Subsection 9.36.5.), and the heat lost through mechanical ventilation counts in the house's total heat loss (9.36.7.3.(5)). An HRV in your house, set against a reference house without one, is a straightforward way to close the gap.

Put plainly: from Tier 2 onward, an HRV is either required or one of the most useful tools a builder has. That matches what Efficiency Nova Scotia sees in the field: "In Nova Scotia, the majority of new homes have an HRV."

If an HRV is installed, it has to perform

Where an HRV provides the house's required ventilation, the energy section sets a floor on how well it recovers heat: at least 60% sensible heat recovery at 0 °C, tested to the Canadian standard CSA C439, with an added test at -25 °C for colder locations (9.36.3.9.(3)). A unit that can't show that rating doesn't count toward the energy rules, whatever it says on the box.

ERVs count

Back to that Reddit answer. The code's explanatory note on HRVs reads, in full: "Enthalpy recovery ventilators (ERVs) are a type of heat recovery ventilator and must therefore comply with the requirements of Article 9.32.3.12." (Note A-9.32.3.12.). So the national code doesn't exclude ERVs; it treats them as HRVs.

We haven't read Nova Scotia's provincial amendments (more on that in the Sources section), so if a builder tells you an ERV isn't allowed, ask which clause, and check with the building official. Whether an ERV is the right choice is a different question, about humidity rather than code. We work through it in ERV vs HRV in Nova Scotia.

Older homes: no requirement, but watch what changes

The code applies to "the design, construction and occupancy of all new buildings, and the alteration, reconstruction, demolition, removal, relocation and occupancy of all existing buildings" (Division A, 1.1.1.1.(1)). Its explanatory note then says what that does not mean: "It is not intended that the NBC be used to enforce the retrospective application of new requirements to existing buildings … unless specifically required by local regulations or bylaws."

So a 1960s bungalow in Dartmouth isn't out of code for lacking an HRV, and nobody can make you add one because the code changed. Efficiency Nova Scotia agrees on the physics: older homes "generally have natural air leakage through cracks and holes in the building and therefore do not need a dedicated ventilation system."

The catch is the word generally. Leaky houses ventilate themselves, at a heating cost, and the work people do to cut that cost also cuts the ventilation:

• New windows and air sealing. Natural Resources Canada describes owners replacing leaky windows and finding condensation gets worse, and says a house tightened that far "will now need more ventilation."
• Heating conversions. NRCan notes that sealed-combustion equipment reduces air changes and "may cause humidity levels to rise." Removing an oil furnace and its chimney takes away a constant draft. That's our reading of the same mechanism, not NRCan's words.

The sign is usually on the glass: windows that run with water on cold mornings, musty closets, mould at the corners. Our window condensation guide shows how to tell, and what an HRV is and why Halifax homes need ventilation covers the system itself. In that house, an HRV isn't a code item. It's the fix.

Renovations, additions and basement suites

Because the code applies to alterations, work you do under a permit is designed to the current code for the work being done. How far that reaches into the rest of the house's ventilation is the building official's call, and it varies with the project. Ask at the permit stage, not after the drywall is up.

A secondary suite is the clearest case. It needs its own self-contained mechanical ventilation system, and no ductwork may connect it to the main house. The code doesn't name an HRV there either, though one is the usual answer in a tight basement apartment. We cover the rules, the clauses and the order of work in ductwork and ventilation for a secondary suite in Nova Scotia.

What "installed to code" looks like

Here the answer to "is it required?" matters less than "is it done right?" When an HRV provides a home's required ventilation, the code sets out how it goes in. These are the points we check on every install and every replacement:

Efficiency Nova Scotia adds one practical rule we'd put on the list: the ventilation system "shouldn't be connected directly to a kitchen range hood," because cooking grease can clog the core. The range hood exhausts outside on its own.

Most of the HRV problems we're called to don't come from the machine. They come from that table: a unit nobody balanced, an intake a metre from the dryer vent, a condensate line that freezes in an unheated corner. Our HRV installation cost guide explains why the ducting and commissioning, not the box, are most of the job.

Where we fit in

We install and replace HRVs and ERVs, run the ducting, and balance them, across Halifax Regional Municipality. Ventilation is air-side work, which is our trade. We're not your building official, and on a permit job the official's reading of the code governs. What we can do is tell you, before you buy anything, what your house actually needs and what installing it properly involves. We don't quote prices before we've seen the house.

Sources

This page makes no cost claims. Code text is quoted from the primary documents below, which we downloaded and read for every clause cited. Last verified October 12, 2026. All sources are Canadian: building code requirements are one of the categories where we never use a non-Canadian source.

Canadian sources

• National Research Council of Canada: National Building Code of Canada 2020, free from the NRC Publications Archive.
  • Volume 1, Division A: 1.1.1.1.(1) (application to new buildings and to alterations of existing ones) and Note A-1.1.1.1.(1) ("not intended … to enforce the retrospective application of new requirements to existing buildings").
  • Volume 2, Division B, Section 9.32: 9.32.1.2.(1)–(2) (required ventilation); 9.32.3.1.(1)–(2) (the three ways to comply and the three components); 9.32.3.2.(3) and (5) (resilient mounting, access); 9.32.3.3.(2), (3), (5) and Table 9.32.3.3. (principal fan capacity by bedrooms; "a single fan, by the exhaust side of a heat recovery ventilator, or by a group of fans"; the "VENTILATION FAN" switch); 9.32.3.4.(5)–(6) (outdoor air into a forced-air system); 9.32.3.5. (separate outdoor-air supply and its distribution); 9.32.3.6.(1) (exhaust-only systems and their conditions); 9.32.3.7. (supplemental exhaust); 9.32.3.12.(4)–(5) (HRV start-up, balancing, condensate); 9.32.3.13.(2)–(4) (intake height and separations); Note A-9.32.3.12. (ERVs are a type of HRV).
  • Volume 2, Division B, Section 9.36: 9.36.2.6.(1) and Note A-9.36.2.6.(1) (insulation tables with and without heat recovery); 9.36.3.9.(1) and (3) and Note A-9.36.3.9.(1) (HRV performance floor, and how 9.32 and 9.36 relate); Subsection 9.36.5. ("the reference house shall be modeled without a heat-recovery ventilator"); 9.36.7.3.(5) (mechanical ventilation in the annual heat loss); 9.36.8.9.(3) (HRV required on the prescriptive tier path); Table 9.36.8.2. (that path's points for Tier 2; higher tiers "Reserved").
• Province of Nova Scotia: news release, 20 September 2024, Province to Adopt 2020 National Building Codes. Source of the 1 April 2025 adoption and the tier schedule (Tier 2 of the building code 1 April 2026; Tier 3 1 April 2027).
• Efficiency Nova Scotia: Ventilation for New Homes. Source of "the majority of new homes have an HRV," the statement that the national code requires mechanical ventilation in all new homes, older homes generally not needing a dedicated system, and not connecting the ventilation system to a range hood.
• Natural Resources Canada: Keeping the Heat In, Section 2: How your house works (a tightened house "will now need more ventilation") and Section 9: Operating your house (sealed-combustion equipment reducing air changes).

What we could not source, and what we left out

• Nova Scotia's provincial amendments. We read the national code and the province's announcement of how it is being phased in. We did not read the provincial regulation itself; an earlier attempt to open it found it unavailable at its published address. If an amendment changes any clause on this page, the provincial text governs, and your building official has the final word.
• Which compliance path your builder uses. It's a design decision, and it's what decides whether an HRV is required by name. Ask your builder or designer.
• How HRM inspectors treat ventilation on renovations. The code leaves the scope of an alteration to the authority having jurisdiction. We don't guess at it.
• Costs. None given, on purpose. See our HRV installation cost guide for published Canadian ranges.