Heat Pumps in New Construction: Sizing, Distribution, and Cold-Climate Selection in HRM

For a new multi-unit building in Halifax Regional Municipality, the heating-and-cooling decision is not an afterthought to be settled once the structure is up. It is a feasibility input. The mechanical strategy a parcel will support — ductless heads, a ducted air handler, central plant — interacts with the energy code now in force, with the financing structure, and with the operating economics the building will carry for decades. At Helio, a computation-driven real-estate development company in Halifax, that interaction is something we model at the feasibility stage, before a design is locked.

This guide explains how heat pumps fit into new construction in HRM in 2026: how systems are sized against real load, how heat is distributed in a multi-unit building, how to read cold-climate performance ratings, and the regulatory and incentive context that frames every one of those choices. It is written from the perspective of a development firm planning what a site can become — not a contractor quoting a job.

Why the energy code makes the mechanical decision early

Nova Scotia's building regulation now adopts the National Building Code of Canada 2020, the National Energy Code of Canada for Buildings 2020, and the National Plumbing Code 2020, in force April 1, 2025 under N.S. Reg. 198/2024 [1]. The province is phasing in the tiered energy requirements on a published schedule: building-code Tier 1 and energy-code Tier 1 took effect April 1, 2025; building-code Tier 2 on April 1, 2026; energy-code Tier 2 on April 1, 2027; and the higher tiers thereafter [2].

For houses and small buildings, the relevant lever is Section 9.36 of the code (energy efficiency), where the tiered performance and prescriptive requirements (Subsections 9.36.7 and 9.36.8) for climatic Zone 6 apply. As of April 1, 2026, at least Tier 2 applies to housing and small buildings in Nova Scotia, having phased in from Tier 1 the year before [3]. Whether a project follows the Part 9 path at all depends on its scale: under the code as adopted, a building qualifies for the simpler Part 9 ("Housing and Small Buildings") route only if it is three storeys or fewer in building height, has a building area of not more than 600 m² (about 6,460 sq ft), and is not an excluded occupancy; exceed either size threshold and it becomes a Part 3 building [4].

The practical consequence: a heat-pump-led envelope is one of the most direct ways to meet a rising energy tier, and the tier a project must satisfy is fixed by its permit timing and its Part 9 / Part 3 classification — both of which are known at feasibility, not at finishing. That is why we treat the mechanical concept as a planning input rather than a late trade decision.

Sizing against load, not square footage

A heat pump that is too large short-cycles — switching on and off repeatedly, which wears components, swings indoor temperature, and undercuts efficiency. One that is too small runs continuously and leans on backup electric resistance heat to keep up. Neither outcome is acceptable in a building that has to hold its operating numbers for the life of the asset.

The correct method is a load calculation that accounts for the building's actual heat loss and gain, not a rule of thumb tied to floor area. The inputs that matter are concrete:

• Envelope performance. Insulation levels, window and door specifications, and air-tightness drive the heating load far more than raw square footage. A Tier 2 envelope under the 2026 code carries a materially different load than an older-stock baseline.
• Climate. HRM sits in code climatic Zone 6, with design conditions cold enough that the system has to hold capacity well below freezing.
• Internal gains and use. Occupancy, appliances, and how each unit is used affect the net heating and cooling demand, and they vary unit-to-unit in a multi-residential building.
• Zoning of demand. Corner and top-floor units carry more exposure than interior units; sizing that ignores room-by-room variation will leave some units over-served and others short.

In a multi-unit context, this is where development economics and design meet. Sizing each unit to its true load — rather than over-specifying a uniform system across the building — keeps capital cost honest and keeps the operating bill defensible. It also feeds directly into any energy-modelled financing pathway, discussed below.

Distribution: how the heat actually reaches the units

Once load is understood, the question is how to deliver it. For new multi-unit construction in HRM, the realistic options each carry different cost, efficiency, and tenant-control profiles.

Ductless mini-split (and multi-split) systems require no central ductwork. Indoor heads are matched to zones, and a multi-split connects several indoor heads to one outdoor unit. The appeal in a new build is flexibility — capacity can be matched to each unit's load and each occupant gets independent control. Efficiency Nova Scotia notes that properly used ductless heat pumps can deliver up to three times the energy they consume [5]. The trade-off is the visible indoor head and the per-zone equipment count.

Variable Refrigerant Flow (VRF) systems connect many indoor units to outdoor condensers and can heat some zones while cooling others simultaneously. They offer the most precise zoning and high efficiency, which suits larger buildings with diverse exposures — at a higher installed cost and a requirement for specialised servicing.

Central ducted systems move conditioned air through shared or per-unit ductwork. They are familiar to design and install, but duct runs introduce thermal and leakage losses, and in a multi-unit building, central ducting raises questions of metering, control, and fire separation that have to be solved in the design phase, not after.

Packaged terminal units (PTACs) are simple, individually controlled, wall-mounted units. They are easy to install but are generally the least efficient option and are rarely the right answer for purpose-built rental being designed to a modern energy tier.

The distribution choice is not purely a comfort question. It changes the building's modelled energy performance, the metering strategy, and the maintenance obligation that flows to operations. We model these together because a distribution decision that looks cheap on day one can erode net operating income across the hold.

Reading cold-climate performance honestly

"Cold-climate" is a marketing phrase unless it is tied to a tested standard. The reliable benchmark is the ENERGY STAR Cold Climate designation, which requires a heat pump to demonstrate low-ambient performance — a coefficient of performance (COP) of at least 1.75 at 5°F (about -15°C) and retention of roughly 70% of rated heating capacity at 5°F compared with 47°F [6]. A unit carrying that designation has been tested to hold useful capacity in conditions that approximate a Nova Scotia cold snap, rather than relying on a nameplate figure measured at mild temperatures.

Beyond the certification, the features that distinguish a system built for this climate are specific: variable-speed compressors and inverter technology that modulate output to demand instead of cycling; a defrost strategy that manages frost on the outdoor coil (Efficiency Nova Scotia notes that a brief defrost pause, with steam or dripping at the outdoor unit, is normal winter behaviour) [5]; and integrated controls that govern when, if ever, a backup heat source engages.

That last point matters for operating cost. Efficiency Nova Scotia's guidance is that a heat pump should serve as the primary heat source for most of the winter, with backup reserved for extreme cold — not everyday use [5]. A design that leans on electric-resistance backup too readily will quietly inflate the building's heating bill regardless of how efficient the heat pump itself is. For a building being underwritten on its operating numbers, that is a feasibility risk, and it is governed by control strategy as much as by equipment selection.

The financing and incentive context

Mechanical strategy intersects directly with how a project is capitalised, which is why we model it alongside the financing structure rather than after it.

CMHC MLI Select — the agency's multi-unit mortgage loan insurance product — awards points across three categories: affordability, accessibility, and climate compatibility (energy efficiency) [7]. Energy points are earned by achieving percentage reductions in energy use and greenhouse-gas emissions over baseline building-code performance [8]. A heat-pump-led, well-modelled building is one of the cleaner ways to accumulate those climate points, which (combined with affordability and accessibility points) move a project across MLI Select's thresholds. Under the program's tiers, 50 points can reach up to 95% loan-to-cost on new construction with up to 40-year amortization, with higher point totals unlocking longer amortization and larger premium discounts [9]. As of the schedule effective July 14, 2025, a minimum 50 points earns a 10% premium discount, 70 points 20%, and 100 points 30% [10]. The mechanical and envelope decisions, in other words, are partly a financing decision.

Accelerated capital cost allowance. Eligible new purpose-built residential rental buildings can be depreciated at an accelerated 10% CCA rate (instead of the usual 4% Class 1 rate) where construction begins on or after April 16, 2024 and before 2031, and the building is available for use before 2036 [11]. This is part of the operating math for a rental asset and is independent of the equipment chosen — but it interacts with the after-tax return that a more-efficient building generates.

Efficiency Nova Scotia programs. For new commercial, institutional, and multi-unit residential projects of at least 15,000 ft² in the pre-construction design phase, Efficiency Nova Scotia's Commercial New Construction program offers a modeling incentive of up to $15,000 toward consultant fees plus an implementation incentive of roughly $0.13–$0.18 per kWh of verified electricity savings (as of June 2026) [12]. For affordable multifamily rental, co-op, shelter, and non-profit support properties, the Affordable Housing Energy Program is open and reported to cover a high share of eligible project costs (as of June 2026) [13]. The federal Oil to Heat Pump Affordability program, administered provincially by Efficiency Nova Scotia, remains active and is oriented to converting existing oil-heated homes — its reported maximum (up to roughly $15,000) is income-tied — so it is a retrofit instrument rather than a new-construction subsidy [14].

We cite these figures as the programs and authorities publish them. Helio does not quote a price of its own; the numbers above are the official ones, current as of June 23, 2026, and program terms change.

How this fits the development process

The throughline is that the heat-pump question is a feasibility question. The energy tier the building must meet is set by its permit timing and Part 9 / Part 3 classification [4]. The load is set by the envelope and the climate zone, and it determines equipment selection rather than the other way round. The distribution strategy shapes both capital cost and the operating bill the asset carries. And the financing pathway — MLI Select climate points in particular — rewards getting the energy story right early [7][8].

Helio computes what a parcel can support and develops it end-to-end for a fee, on land its clients own, with construction delivered by established builders. Resolving the mechanical and energy strategy at the feasibility stage — against the code in force, the financing structure, and the operating model — is part of how the most that a site can become gets translated into a building that performs once it is occupied.

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Sources

1. Government of Nova Scotia — News Release, "Province to Adopt 2020 National Building Codes" (Sept 20, 2024). https://news.novascotia.ca/en/2024/09/20/province-adopt-2020-national-building-codes
2. Government of Nova Scotia — National building code tier phase-in schedule (per the Sept 20, 2024 news release). https://news.novascotia.ca/en/2024/09/20/province-adopt-2020-national-building-codes
3. Government of Nova Scotia — Building Code Regulations §9.36 (Subsections 9.36.7 / 9.36.8), tier dates per the Sept 20, 2024 release. https://news.novascotia.ca/en/2024/09/20/province-adopt-2020-national-building-codes
4. National Research Council Canada — Illustrated User's Guide, National Building Code of Canada 2020, Part 9 (Division B), Housing and Small Buildings. https://nrc.canada.ca/en/certifications-evaluations-standards/codes-canada/codes-canada-publications/illustrated-users-guide-national-building-code-canada-2020-part-9-division-b-housing-small-buildings
5. Efficiency Nova Scotia — "Your Guide to Heat Pumps and Extreme Cold." https://www.efficiencyns.ca/tools-and-resources/blog/your-guide-to-heat-pumps-and-extreme-cold
6. ENERGY STAR — Version 6.2 Central Air Conditioner and Heat Pump Specification (Cold Climate designation criteria). https://www.energystar.gov/sites/default/files/2024-12/ENERGY%20STAR%20Version%206.2%20Central%20Air%20Conditioner%20and%20Heat%20Pump%20Final%20Specification_1.pdf
7. CMHC — MLI Select. https://www.cmhc-schl.gc.ca/professionals/project-funding-and-mortgage-financing/mortgage-loan-insurance/multi-unit-insurance/mliselect
8. CMHC — MLI Select (energy-efficiency / climate-compatibility criteria). https://www.cmhc-schl.gc.ca/professionals/project-funding-and-mortgage-financing/mortgage-loan-insurance/multi-unit-insurance/mliselect
9. CMHC — MLI Select program PDF (point thresholds and amortization). https://assets.cmhc-schl.gc.ca/sites/cmhc/professional/project-funding-and-mortgage-financing/mortgage-loan-insurance/multi-unit-insurance/mliselect/mli-select.pdf
10. CMHC — Notice: CMHC to Update Multi-Unit Mortgage Loan Insurance Premiums (premium discount schedule effective July 14, 2025). https://www.cmhc-schl.gc.ca/media-newsroom/notices/2025/cmhc-to-update-multi-unit-mortgage-loan-insurance-premiums
11. Budget 2024 — Tax Measures: Supplementary Information (Accelerated CCA for Purpose-Built Rental Housing). https://www.budget.canada.ca/2024/report-rapport/tm-mf-en.html
12. Efficiency Nova Scotia — Commercial New Construction. https://www.efficiencyns.ca/programs-rebates/commercial-new-construction
13. Efficiency Nova Scotia — Affordable Housing Energy Programs (Affordable Multifamily Housing). https://www.efficiencyns.ca/programs-rebates/affordable-housing-energy-programs
14. Efficiency Nova Scotia — Oil to Heat Pump Affordability Program. https://www.efficiencyns.ca/programs-rebates/oil-to-heat-pump-affordability-program