What Is the MVDS in Ontario? The Mechanical Ventilation Design Summary — Mandatory Under OBC 2024
The Mechanical Ventilation Design Summary (MVDS) is a document required under OBC 2024 for every new home and second suite in Ontario. It replaced the informal practice of selecting an HRV or ERV based on equipment availability and attached it to the building permit process — meaning an MVDS must be submitted with the permit application, not installed and assumed compliant after the fact.
The MVDS was mandatory from January 1, 2025, and enforced for all building permit applications from April 1, 2025. Every application submitted after that date without an MVDS is returned as incomplete before any technical review begins — regardless of how complete the rest of the HVAC package is. This guide explains what the MVDS is, what it must contain, who can produce it, and how it fits into the complete Ontario building permit package. For the MVDS as part of our full service, see our HRV/ERV design service.
Before OBC 2024, Ontario's building code required homes to have mechanical ventilation systems — HRVs or ERVs — but the documentation requirements for the ventilation design were less prescriptive than for the heating system. OBC 2024 changed this by requiring a formal Mechanical Ventilation Design Summary to be produced by a BCIN-registered designer and submitted with the building permit application. The MVDS brings ventilation design into the same documented, reviewed, permit-stamped framework as the CSA F280 heat loss calculation.
The underlying standard the MVDS documents compliance with is CAN/CSA-F326, "Residential Mechanical Ventilation Systems." This standard sets minimum ventilation rates for residential buildings, specifies HRV and ERV performance requirements including Sensible Recovery Efficiency (SRE) testing conditions, and defines the distribution system requirements for mechanical ventilation. The MVDS is the document that demonstrates the proposed ventilation system meets these requirements for the specific home being permitted.
The building department reviewer checks for the MVDS as a first-pass completeness check — before any technical review of the heat loss calculation, mechanical drawings, or other documents begins. An application submitted without the MVDS is returned as incomplete. The review clock does not start. In municipalities with long review timelines — Tiny Township's standard one-month review, for example — a returned application resets the clock to zero. The cost of including the MVDS in the permit package upfront is a fraction of the cost of a permit delay caused by resubmission. See our permit rejection guide for the full list of rejection causes.
Ventilation Equipment Selection
The specific HRV or ERV model selected for the home — manufacturer, model number, and equipment type. The MVDS must document actual equipment, not a generic "HRV to be determined" placeholder. The equipment selection is what the rest of the MVDS is built around — the performance data in the MVDS derives from the specific model's tested performance.
Total Ventilation Capacity
The confirmed total ventilation capacity of the selected HRV or ERV in litres per second (L/s) at the operating conditions specified in CAN/CSA-F326. The capacity must meet or exceed the minimum ventilation requirement for the home's floor area and occupancy. The MVDS documents the calculation that confirms compliance.
Sensible Recovery Efficiency at -25°C
The SRE at -25°C is the HRV or ERV's thermal efficiency at the coldest test condition under CAN/CSA-F326. This is a key performance metric — particularly relevant for Zone 6 and Zone 7 homes where the ventilation system must handle significant temperature differentials. The MVDS must document the specific model's tested SRE at -25°C from certified test data, not from marketing materials.
SB-12 Compliance Path
Ontario's Supplementary Standard SB-12 sets energy efficiency requirements for residential buildings. The MVDS must identify which SB-12 compliance path the home is following and confirm that the ventilation system meets the energy performance requirements of that path. For homes following prescriptive compliance paths, the MVDS confirms the HRV or ERV meets the SRE threshold required by that path.
Ventilation Distribution
Documentation of how fresh air is distributed throughout the home — whether through the forced-air duct system, dedicated HRV supply ducts, or a combination. For homes with central forced-air systems, the MVDS confirms the integration of the HRV's fresh air supply with the duct distribution. For homes without forced air, the MVDS documents the standalone distribution approach.
BCIN Stamp and Designer Declaration
The MVDS must be produced and stamped by a BCIN-registered designer — the same designer who stamps the heat loss calculation and mechanical drawings. The BCIN stamp must appear on the MVDS document. In practice, the MVDS is typically produced as one of the package documents alongside the CSA F280 and mechanical drawings, all stamped by the same designer. See our HVAC signing authority guide.
The MVDS requirement is the same province-wide, but the SRE performance threshold that matters most varies by climate zone.
Zone 5 — GTA & York Region (-18°C)
At -18°C, HRV operation at or below the CAN/CSA-F326 -25°C test condition occurs only occasionally. SRE at -25°C still matters for the MVDS but the performance gap between a high-SRE and standard HRV is less impactful than in colder zones. The MVDS documents the selected unit's SRE at -25°C as required — equipment meeting SB-12's minimum SRE threshold is typically straightforward to specify. See our Newmarket HVAC guide.
Zone 6 — Simcoe County (-22°C to -24°C)
In Zone 6, the -25°C test condition is closely approached or reached during the coldest winter nights. SRE at -25°C is directly relevant to real-world performance — an HRV with poor low-temperature efficiency will defrost frequently and deliver reduced ventilation during the coldest periods. The MVDS should document a unit with genuine high SRE at -25°C, not just one that passes the minimum threshold on paper. See our Barrie heat loss guide.
Zone 7 — Muskoka (-28°C)
In Zone 7, outdoor temperatures regularly exceed the -25°C test condition. SRE at -25°C is the most directly relevant performance metric for Muskoka HRV selection — and the MVDS must document a unit that can operate effectively at these conditions without excessive defrost cycling that reduces actual ventilation delivery. Specifying the right HRV for Zone 7 is more consequential than in any other Ontario zone. See our Muskoka heat loss guide.
What is the MVDS and when was it made mandatory in Ontario?
The MVDS (Mechanical Ventilation Design Summary) is a document required under OBC 2024 that formally documents the HRV or ERV system for a new home — equipment selection, ventilation capacity, SRE at -25°C, and SB-12 compliance path. It was made mandatory under OBC 2024 from January 1, 2025, with enforcement for all new permit applications from April 1, 2025. Every new home permit application submitted after January 1, 2025 must include the MVDS.
Who can produce the MVDS for an Ontario building permit?
The same BCIN-registered designer who produces the CSA F280 heat loss calculation and mechanical drawings — a designer holding an active HVAC-House (or HVAC-General) qualification. The MVDS must be BCIN-stamped. In practice it is produced as part of the complete permit package, not as a standalone document. See our BCIN guide and our signing authority guide.
Does the MVDS require a specific HRV to be chosen before the permit is submitted?
Yes — the MVDS must document actual, specific equipment — manufacturer and model number — not a placeholder. The equipment's tested SRE at -25°C from certified test data, and its confirmed ventilation capacity, are what the MVDS documents. This means the HRV or ERV selection must be made before the permit application is submitted. Changes to equipment after permit approval may require a revised MVDS.
Is the MVDS the same as the HRV/ERV design?
The MVDS is the document — the formal summary that goes into the permit package. The HRV/ERV design is the process that produces the MVDS — the process of selecting appropriate equipment, calculating ventilation rates, verifying SRE at -25°C against the applicable SB-12 path, and documenting how fresh air is distributed through the home. Our HRV/ERV design service produces the MVDS as a standard deliverable in every complete permit package.
Does the MVDS apply to renovations and additions?
The MVDS applies to new homes and to renovation or addition work where the permit involves the mechanical ventilation system. For a new home, it is always required. For an addition or renovation that involves the ventilation system — adding HRV distribution to a new addition, upgrading the HRV, modifying ventilation paths — the MVDS requirement applies. For renovations that do not touch the ventilation system, confirm with your building department whether the MVDS is required for the specific scope of work.
Need an MVDS for your Ontario permit? It's included as standard in every complete package we produce — alongside the CSA F280 heat loss and mechanical drawings. BCIN-stamped, 48 hours.
Get Free Quote →The MVDS is not a standalone add-on — it is a standard component of every complete HVAC permit package we produce. Upload your floor plans and we'll produce the CSA F280 heat loss at your local design temperature, mechanical drawings, MVDS with equipment selection and SRE at -25°C, and Schedule 1 — all BCIN-stamped and delivered in 48 hours. For the full HRV and ERV design service context, see our HRV/ERV design service.
- HRV or ERV selected for your climate zone and home size
- Ventilation capacity confirmed against CAN/CSA-F326 minimums
- SRE at -25°C documented from certified test data
- SB-12 compliance path confirmed and documented
- BCIN stamp on MVDS and all documents · 48h delivery