For a four- to twelve-storey rental building, the HVAC system is one of the largest line items in the budget. It affects floor-to-floor heights, shaft sizes, electrical service, energy performance, tenant comfort and long-term maintenance. There is no single right answer, but there is a right answer for your project.
The common options
Suite-level air-source heat pumps (split or ducted)
Each suite has its own heat pump, typically with an outdoor unit on the roof or balcony and a ducted indoor unit. Suite-level metering is simple, and tenants control and pay for their own comfort. Watch outdoor unit placement, refrigerant piping lengths and cold-climate capacity.
Variable refrigerant flow (VRF)
Centralized outdoor units serve many indoor units through refrigerant piping. VRF offers good part-load efficiency and heat recovery between zones. Refrigerant volume limits in occupied spaces must be designed carefully, and suite billing requires a sub-metering strategy.
Four-pipe fan coils with a central plant
A central boiler and chiller plant, or a heat pump plant, serves fan coils in each suite. This option is flexible and durable, and it adapts well to future fuel switching. The higher capital cost and plant space need to be justified by building size and hold period.
Water-source heat pump loop
Suite heat pumps connect to a building water loop, with heat added or rejected centrally. It can use geo-exchange or waste heat recovery and performs well against energy targets. Loop design and water treatment are critical.
Packaged terminal units (PTACs / PTHPs)
Low first cost and simple to replace, but noisier and less efficient. They make it harder to hit ambitious energy targets and are increasingly rare in new rental construction.
Don’t forget ventilation
Traditional corridor pressurization with gas-fired make-up air is simple, but it wastes energy and does not always deliver fresh air to suites. Suite-level ERVs/HRVs, or central heat recovery ventilation ducted to each suite, generally perform far better on energy and indoor air quality, and often decide whether you reach an MLI Select energy tier.
How we help clients decide
At schematic design, Miriton compares two or three strategies side by side:
- Estimated capital cost and impact on electrical service size
- Annual operating cost and who pays (owner vs tenant)
- Space: shafts, ceiling zones, rooftop and mechanical rooms
- Energy performance against your target (code, municipal standard or MLI Select)
- Maintenance and replacement cycles over your hold period
The result is a decision your architect, cost consultant and lender can all work with. Learn more about our mid-rise work or request a fee proposal.