New build inspection · Heating and ventilation
Heating and ventilation defects in a new build
New homes are built airtight enough that mechanical ventilation is no longer optional, and the ventilation system is the component most often installed but never commissioned.
What goes wrong with heating and ventilation in a new build?
Reviewed · 2026-09-03New homes are built airtight enough that mechanical ventilation is no longer optional, and the ventilation system is the component most often installed but never commissioned.
Why it matters
Heating and ventilation in a new home
A modern Calgary home is far tighter than a house built thirty years ago. That is good for heating costs and bad for air quality, which is why current construction includes a heat recovery ventilator to bring in fresh air and temper it against the outgoing stream.
The recurring problem is not the equipment. It is that the system is installed, energised and never balanced or commissioned, so it runs at whatever the installer left it at. An HRV that is not balanced can pressurise or depressurise the house, and a depressurised house pulls air down flues and up from the basement.
The heating side has its own pattern of defects, most of them in the ductwork rather than the furnace: runs that were never connected, missing dampers, returns that are undersized, and flexible duct crushed behind framing.
Best moment to look
Pre-possession walkthrough
Ask for the commissioning documentation at the walkthrough, then test comfort room by room through the first heating season and report imbalances before the first year ends.
In Alberta
Calgary's winter design temperature makes the heating system the most consequential mechanical decision in the house, and the chinook cycle means it swings between hard running and idling within days. Two practical points. First, ask specifically for the HRV balancing report, because an uncommissioned HRV is common and the fix is a service call rather than an argument. Second, check the exterior intake and exhaust terminations after the first big snowfall, since blocked terminations at ground level are a genuine carbon monoxide risk. Distribution systems generally carry a shorter Alberta New Home Warranty period than the structure, so mechanical complaints need to be raised early.
How it should be built
What correct looks like
How a heat recovery ventilator should be set up
Stale indoor air and fresh outdoor air pass through the core in balanced volumes. An uncommissioned unit runs unbalanced and pressurises or depressurises the house.
The flags
What to look for
Each item lists what the defect is, how to spot it without tools, and the stage of construction when it is still visible. None of this replaces a licensed inspector. It makes you a useful witness on your own site.
01HRV installed but never balanced or commissioned
SafetyWhat it is. A heat recovery ventilator has to be balanced so the volume coming in matches the volume going out, and set to run on a schedule. Without commissioning it may be moving almost nothing, or unbalancing the house.
How to spot it. Ask for the commissioning or balancing report by name. Look at the unit for a label recording the balanced flow rates and the date. Find the control and check it is set to run rather than off.
Visible at: Pre-possession walkthrough
02Duct runs disconnected or crushed
Comfort and costWhat it is. Flexible duct pulls off its collar easily and rigid runs are sometimes never joined. A disconnected branch heats the floor cavity instead of the room above it, and nobody notices until winter.
How to spot it. At pre-drywall, follow each run to its boot. After possession, hold your hand at every register with the fan running; a room with weak flow compared with the rest is the clue.
Visible at: Pre-drywall
03Rooms with supply but no return path
Comfort and costWhat it is. Air blown into a room must have a way out. A bedroom with a supply register, no return and a door that seals will pressurise, push air out through the walls, and stay uncomfortable.
How to spot it. Look for a return grille, a transfer grille or a visible undercut beneath each bedroom door. Close the door with the fan running and see whether it pulls or pushes.
Visible at: Pre-possession walkthrough
04Dryer vent too long, crushed or terminating badly
SafetyWhat it is. Dryer ducting has a maximum length and must not be kinked. A restricted vent is a fire risk and a slow dryer, and one terminating under a deck or into a soffit dumps lint and moisture where it will accumulate.
How to spot it. Find the exterior termination and confirm it has a damper and is clear of soffits and decks. Behind the dryer, look for a crushed or heavily coiled flexible duct.
Visible at: Pre-possession walkthrough
05Combustion air and venting compromised
SafetyWhat it is. Fuel-burning appliances need a reliable air supply and a clear vent. Blocked intakes, vent terminations too close to windows or ground level, and mechanical rooms sealed by a later basement development all create combustion risk.
How to spot it. Outside, find the intake and exhaust terminations and check they are clear of snow accumulation, windows and the ground. Inside, confirm nothing blocks the supply into the mechanical room.
Visible at: Pre-possession walkthrough
06Filter and service access blocked
Comfort and costWhat it is. A furnace filter that cannot be reached will not be changed. Equipment installed with no service clearance costs money at every future repair.
How to spot it. Try to remove the filter yourself at the walkthrough. Check there is room to open the furnace panels and reach the HRV core.
Visible at: Pre-possession walkthrough
07No documented heat loss calculation for the equipment
Comfort and costWhat it is. Furnace and duct sizing should follow a heat loss calculation for the specific house. Oversized equipment short cycles, heats unevenly and wears out faster.
How to spot it. Ask for the heat loss calculation and the duct design. A builder who can produce them on request is telling you something useful.
Visible at: Pre-possession walkthrough
Put it in writing
Questions for the builder
Ask these by email rather than on site. A written answer is a record, and a builder who answers clearly in writing is telling you something useful about how the rest of the build will go.
- Can I have the HRV commissioning and balancing report, and the heat loss calculation?
- How should the ventilation system be set to run in winter, and who shows me?
- Where do the furnace and HRV intake and exhaust terminate, and what snow clearance do they need?
- If a room is uncomfortable in January, what is the process and how long do I have to report it?
FAQ
Questions about heating and ventilation
A heat recovery ventilator brings fresh outdoor air into a tightly built house and exhausts stale air, passing them through a core so most of the heat is recovered. Yes, it should run. A new home generates a lot of moisture in its first year, and the ventilation system is the main way that moisture leaves. Homes where the HRV is switched off tend to be the ones with window condensation complaints.
It can be. Consistent temperature differences between rooms usually trace to a duct problem: a disconnected run, a closed damper, an undersized branch or no return path. Report it in writing during the first heating season, describe the room and the difference, and ask for the system to be balanced. Waiting until the second winter can put it outside the workmanship period.
Construction debris, drywall dust and offcuts do end up in ductwork, and many owners have the system cleaned once after possession for that reason. Ask whether the builder already does a post-construction clean before you pay for one, and be cautious of aggressive cleaning that can disconnect flexible duct runs.
Source note
- Sources
- Alberta New Home Warranty program information
- National Building Code, Alberta Edition, as adopted for the permit in force
- City of Calgary building inspection and lot grading information
- Health Canada radon guidance for homeowners
- Jurisdiction
- Alberta, with Calgary-specific notes
- Applies to
- New residential construction purchased from a builder.
- Last reviewed
- 2026-09-03
- Limitations
- General guidance written for buyers, not a code interpretation and not a substitute for a licensed home inspector or a professional engineer. Code requirements depend on the edition in force when the permit was issued. Warranty periods and coverage depend on your own warranty certificate.
- What you should verify
- The requirements that applied to your permit, the coverage periods on your warranty certificate, and any defect with a licensed inspector before you rely on it in a claim.
Work with REP YYC
Bring your own representative to the walkthrough.
The builder's sales staff are paid to sell the builder's lots. REP YYC agents are paid by the builder too, but they work for you: lot choice, contract terms, incentives and the possession timeline. No cost to the buyer.