MVHR, MEV and PIV: The Merchant's Guide to Stocking Ventilation Systems That Sell

Why Ventilation Demand Is Growing and Won't Stop

The UK construction industry's shift toward tighter, better-performing buildings has passed the point of being design-led. It is now legislatively mandated.

The regulatory picture:

• Part L 2021 significantly raised energy performance standards for new builds. Higher airtightness means less incidental ventilation through gaps in the fabric mechanical systems are now essential to maintain acceptable indoor air quality in compliant properties.
• Part F mandates minimum ventilation provision for new builds and substantially renovated homes. This is not advisory guidance. Non-compliant installs fail building control sign-off.
• The Future Homes Standard will require new homes to produce 75–80% lower carbon emissions than properties built to 2013 standards. When that comes into force, MVHR moves from premium specification to mainstream requirement across a much larger portion of the new build market.
• Passivhaus completions are growing year on year. Every Passivhaus project specifies a high-performance MVHR unit. The pipeline is growing in both private residential and social housing.
• Indoor air quality has received unprecedented regulatory and media attention following the Awaab Ishak case, which placed a legal spotlight on housing providers' obligations to address damp and mould. Housing associations and local authorities have responded with substantial increase in PIV and MEV procurement.

The combination of these drivers means the pipeline of ventilation work doesn't follow market sentiment in the way other building products do. A slowdown in new build starts affects MVHR and MEV sales less than it affects, say, brickwork or timber. Retrofit demand the PIV market is almost entirely insulated from new build cycles.

For merchants, the implication is clear: this category performs through the cycle. The merchants who invest in it now will be better positioned to supply the volume that the Future Homes Standard will generate.

MVHR Understanding the Commercial Opportunity

What the system does

MVHR is the premium tier of residential whole-house ventilation. A central unit draws stale, humid air from wet rooms bathrooms, kitchens, utility rooms while simultaneously delivering filtered fresh air to living spaces and bedrooms. The heat exchanger at the core recovers 85–92% of the thermal energy from the outgoing air stream and transfers it to the incoming supply, without the two airflows ever mixing.

In an airtight new build, this matters enormously. Under Part L 2021, new properties need to demonstrate minimal heat loss. MVHR ensures that maintaining indoor air quality doesn't undermine the energy performance the building was designed to achieve.

Who buys it and why

Housebuilders and developers on Part L-compliant schemes represent the largest and fastest-growing MVHR buyer group. Self-build clients working with architects or Passivhaus designers are a smaller but high-value segment they often buy through merchants after their M&E designer has specified a particular unit. Social housing providers investing in major retrofit programmes are an emerging buyer group for MVHR as they upgrade older stock to higher energy standards.

The contractor profile matters. MVHR is typically specified before site work begins, often by a ventilation designer or M&E engineer. The merchant's role is frequently fulfilment rather than specification which means having everything in stock when the installer arrives is more important than being part of the design conversation.

The accessory opportunity most merchants underestimate

MVHR is where accessories margin is made or lost. A typical residential MVHR installation requires:

• Semi-rigid radial ductwork (the dominant distribution format for residential installs fast to run, flexible enough for tight roof spaces)
• Rigid duct sections for longer runs
• Internal air valves for each room served
• External weatherproof grilles
• Acoustic silencers, particularly where the unit is near sleeping areas
• Duct insulation
• Commissioning equipment (including anemometer or flow meter if the installer doesn't carry their own)
• Replacement filter cartridges the most reliable repeat order in the category

If a merchant can't supply the full accessories package from the same counter, the contractor will find a specialist supplier who can and they'll take the unit purchase with them next time. The filter repeat order alone, every six to twelve months per installation, represents a long-term revenue stream for any merchant who stays close to their MVHR installer base.

Trade insight: Semi-rigid radial duct is one of the fastest-moving lines in a well-stocked ventilation range. Contractors working across a housing scheme can go through several hundred metres on a single project. Hold it well stocked, at the right lengths, and it becomes a reliable category driver in its own right.

MEV The Mid-Tier Product Most Merchants Understock

What the system does

Mechanical Extract Ventilation takes a simpler, lower-cost approach than full heat recovery. A single central fan unit typically loft- or cupboard-mounted draws stale air from wet rooms through a duct network and expels it outside. Fresh air enters passively through trickle vents or wall-mounted inlet grilles. No heat recovery, no supply ductwork, lower installed cost.

For a large segment of the residential new build market, that trade-off is exactly right. MEV meets Part F requirements, measurably outperforms intermittent bathroom fans on indoor air quality, and can be installed across a multi-unit residential development more quickly and cheaply per plot than MVHR. It is the workhorse solution for volume housebuilders who need compliance without the cost premium.

Who buys it

Volume housebuilders building to standard energy targets rather than Passivhaus or premium EPC specifications represent the core MEV market. Social housing contractors upgrading older multi-room extract systems account for a growing retrofit segment. Developers building apartment blocks or converted properties where threading full supply ductwork through every unit would be impractical are consistent buyers. MEV has also gained traction as a replacement for aging whole-house intermittent fan installations where building regulations require an upgrade on renovation.

The stocking case

MEV doesn't carry MVHR's accessory depth, but it isn't a bare unit sale either. Every installation needs extract ductwork, internal valves, and external grilles. On a housing scheme of twenty or thirty units, that volume adds up meaningfully. The stocking overhead is modest a compact range, predictable turnover, and limited returns make MEV a low-risk category addition for merchants not yet fully committed to ventilation.

Where merchants leave money on the table: Trickle vent components. Contractors installing MEV systems almost always need to upgrade or add trickle vents as part of the passive supply side of the installation. If those components aren't on the shelf, you've lost a sale that was already in the building.

PIV The Volume Driver Merchants Should Prioritise

What the system does

Positive Input Ventilation is the highest-volume product in the residential ventilation category for most merchants. A single loft-mounted unit draws fresh, filtered air from outside and pushes it gently into the property through a ceiling diffuser, creating positive pressure that encourages stale and moisture-laden air to exhaust through natural gaps in the building fabric. No duct network. No complex commissioning. Typically installed in half a day.

PIV systems are deployed almost exclusively as a retrofit solution primarily to address condensation, surface mould, and poor indoor air quality in older properties that weren't designed for mechanical ventilation.

The market reality

The PIV market is driven by social housing. Housing association maintenance teams running rolling programmes to address damp and mould in older housing portfolios are among the most consistent buyers in the entire building products sector. Once a contractor or maintenance team establishes a supplier relationship, they come back regularly not just for PIV units, but for any associated components.

These accounts behave differently from new build project buyers. There's no tender cycle or scheme-based procurement it's a steady stream of orders as properties come up for treatment. For merchants, that means predictable, plannable demand with low volatility.

Private landlords managing damp issues in older rental properties, and retrofit specialists working across local authority referral programmes, add further volume to the market. Following the heightened regulatory and media focus on damp and mould, demand from housing associations has materially increased. The Awaab Ishak case was a catalyst procurement teams that had been deferring large-scale PIV rollouts have accelerated those decisions.

The stocking proposition

PIV is the simplest category proposition in residential ventilation. Units are compact, return rates are low, and most installations need minimal additional materials. Some units include an integral heating element, reducing the accessories requirement further. Stock requirements are manageable; sell-through is steady; the customer relationships that come with the territory tend to be long-term.

The risk is treating PIV as a commodity. The contractors buying regularly are worth knowing by name.

Which Systems Generate the Best Margins?

The MVHR margin case

The MVHR unit itself carries reasonable margin for merchants, but the real case for the category is the accessories package. A standard MVHR installation in a four-bedroom new build might require:

• 80–120m of semi-rigid radial ductwork
• 6–10 internal air valves
• 2–4 external weatherproof grilles
• Silencers on bedroom supply runs
• Duct insulation for loft runs
• Commissioning meter
• First-year filter replacement

That accessories package can easily add £400–£800 to an order on top of the unit. Over the life of an installation, filter replacements alone typically every six to twelve months represent an ongoing revenue stream per property that requires minimal counter effort to service.

The merchant who captures the accessories sale on every MVHR unit they sell is making substantially more per customer than the one who sells units alone.

The PIV repeat order logic

PIV margins per unit are lower than MVHR. But the volume and consistency of the market means the aggregate margin case is strong. A housing association running a programme across several hundred properties over two to three years is a predictable revenue source. Getting onto an approved supplier list for that kind of programme, and maintaining the relationship through reliable stock and service, creates a business line with very low acquisition cost.

Which Systems Generate the Highest Repeat Sales?

MVHR filter orders are the category's most underutilised repeat revenue stream. Most merchants make the initial MVHR accessories sale but lose the filter repeat to online channels or specialist suppliers. Simple measures keeping customer installation records, proactive filter reminders, holding stock consistently recover those orders with minimal effort.

PIV programme buying is the highest-volume repeat mechanic in the category. Maintenance teams don't want to shop around. A merchant who is reliably stocked, easy to invoice, and occasionally picks up the phone is protecting a long-term account.

Common Merchant Stocking Mistakes

1. Stocking the unit but not the accessories. This is the single most common category management error. An installer who orders an MVHR unit and has to source ductwork, valves, and grilles elsewhere will consolidate with the supplier who can do it all. The unit sale is the entry point; the accessories sale is where the relationship and the margin lives.

2. Holding semi-rigid duct in too short a range. Semi-rigid radial duct comes in different diameters and lengths. Contractors working to a manufacturer's system design will need specific sizes. If the range is incomplete, they'll source the whole duct order elsewhere rather than splitting suppliers.

3. Treating PIV as a low-priority line. Because PIV units are lower in price than MVHR, they can get deprioritised in a category plan. That's a mistake. The unit volume and consistency of the PIV market especially through housing association and social housing channels makes it one of the more reliable revenue lines in the building products category.

4. Not stocking replacement filters. Filters are a high-margin, low-competition accessory. Installers who bought their MVHR unit through a merchant expect to be able to buy replacements there too. If those filters aren't available, that repeat business moves online.

5. Under-training counter staff. Ventilation has a higher technical threshold than most building products, but it doesn't require engineering knowledge. Counter staff need enough product literacy to ask the right qualifying questions property type, new build or retrofit, target compliance standard and direct the customer appropriately. Teams without that literacy lose orders that a better-prepared counter would have converted.

6. Over-concentrating on one system type. Merchants who stock only PIV, or only MVHR, are leaving significant business with the other two categories. The customer who arrives for a PIV unit today might be spec'ing a new build development next year. Demonstrating full category capability builds account depth.

Accessories Merchants Should Never Ignore

This is where the category makes or loses money.

Semi-rigid radial ductwork is the essential stocking item for any merchant selling MVHR or MEV systems. It is the dominant duct format for residential installs flexible enough to route through tight roof spaces, fast to install, and consumed in volume across any scheme of scale. Merchants who hold it consistently develop a competitive advantage that's difficult for specialists to undercut on service.

Internal air valves are sold in multiples per installation. A four-bedroom MVHR installation typically needs six to ten valves. They're low individual price, high collective volume, and simple to stock.

External weatherproof grilles are needed on every MVHR and MEV installation supply and extract. There are aesthetic as well as functional considerations for developers and housing associations. Having a choice of profile and finish can make a difference on specification projects.

Acoustic silencers are frequently forgotten until an installer has a problem. They're most critical on bedroom supply runs. Counter staff who proactively raise silencers at the point of an MVHR unit sale recover accessory revenue that would otherwise be lost.

Replacement filter cartridges are the single most reliable repeat revenue line in the MVHR accessories range. Every system needs them. The purchase cycle is regular. The barriers to switching supplier are low which means consistent stock and simple ordering are the primary retention tools.

Commissioning equipment anemometers and flow meters is a lower-volume but high-margin line. Not every installer carries their own. If yours don't, having the equipment available (to sell or hire) builds goodwill and basket value.

How Regulations Are Reshaping the Category

The regulatory environment has fundamentally changed the scale of the ventilation market. Understanding the direction of travel helps merchants make better stocking and ranging decisions.

Part L 2021 is the legislation most immediately relevant to current demand. The updated Approved Document L raised energy efficiency requirements for new dwellings, driving higher airtightness targets that make mechanical ventilation a compliance necessity rather than a premium upgrade. Housebuilders who might previously have relied on background ventilation through the building fabric now need a whole-house mechanical system.

Part F sets out the minimum ventilation rates for dwellings. Mechanical systems MVHR, MEV, or continuous mechanical extract are the specified routes to compliance for new builds. This is not a guideline document; it is a mandatory technical standard.

The Future Homes Standard is the most significant regulatory development on the horizon. Currently in development, it is expected to require new homes to produce 75–80% less carbon than properties built under 2013 regulations. When implemented, this will substantially increase the proportion of new builds specifying MVHR over lower-cost extract-only systems, because the heat recovery performance is needed to maintain the energy balance in highly airtight fabric.

Merchants who are well positioned in MVHR before the Future Homes Standard takes full effect will be better placed to capture that demand. Building supplier relationships, staff knowledge, and stock depth now means those accounts are already consolidated when volume increases.

The mould and condensation driver operates largely independently of new build regulations. Social housing providers have faced increasing legal, regulatory, and media pressure to address damp and mould in existing stock. That pressure has converted into real procurement spend on PIV systems. It's a market driver that is unlikely to diminish the properties that need treatment are already there, and the obligation to treat them has become unambiguous.

What Contractors Actually Need From a Merchant

Ventilation contractors are not price-driven in the way some trade buyers are. The primary purchase criteria, in order, are typically:

1. Stock reliability. A ventilation contractor working to a project programme cannot afford delays. If a merchant consistently has the right units and accessories available, that reliability is worth a premium. Persistent out-of-stocks lose accounts that would otherwise be loyal.

2. Range completeness. Contractors want to order from one place. A merchant who can supply the MVHR unit, the ductwork, the valves, the grilles, and the filters in a single transaction earns a purchasing consolidation premium that specialists find hard to compete with on pure price.

3. Product knowledge at the counter. Not engineering depth but enough confidence to confirm stock, suggest the right accessories for the system being installed, and handle simple technical queries without making the contractor wait. Contractors who encounter informed, confident counter staff return. Contractors who encounter blank looks find another supplier.

4. Account terms and invoicing. For contractors running multiple schemes simultaneously, credit terms and straightforward invoicing matter. This is often a differentiator between merchants competing for the same account.

5. Support when things go wrong. Returns handling, access to technical support, and a direct point of contact when a project throws up an unexpected challenge build loyalty more reliably than price concessions.

How to Build a Profitable Ventilation Category

Start with PIV. The stocking overhead is low, the demand is consistent, and the buyer relationships tend to be straightforward. A small range of well-chosen PIV units generates revenue immediately and builds category credibility.

Add MEV as the mid-tier. A core MEV range unit, extract ductwork, valves, and grilles covers the volume new build and social housing retrofit market without requiring a large inventory investment. The sell-through is predictable.

Commit to MVHR with the full accessories package. MVHR is the highest-margin category, but only if the accessories are available. A merchant who sells MVHR units without ductwork, valves, and filters is underperforming the category's potential. A full-range commitment takes more shelf space and more supplier coordination, but the per-customer revenue and the long-term account value from filter repeats justifies it.

Build the filter repeat order system. Hold customer records. Know which MVHR units are installed and when they'll need filter replacements. Reach out proactively. This is an almost costless revenue stream that most merchants leave on the table.

Train the counter. A half-day investment in product training per staff member converts meaningfully in a category where most competitors haven't bothered. Quiet-Vent provides counter training support for merchant partners the basics don't take long.

Identify and protect key accounts. Housing association maintenance teams, volume contractors, and housebuilder approved supplier relationships generate predictable, large-volume revenue. They're worth identifying specifically and managing proactively.

Working With Quiet-Vent

Quiet-Vent supplies the full residential ventilation range — MVHR units, MEV systems, PIV units, semi-rigid radial ductwork, rigid duct sections, internal air valves, external weatherproof grilles, silencers, insulation, filters, controls, and commissioning accessories. Everything a merchant needs to run a complete, commercially credible ventilation category from a single supplier relationship.

We work with builders' merchants, independent trade counters, and ventilation distributors across the UK and Ireland. Our offer to merchant partners includes reliable stock availability, competitive pricing structured for trade margin, counter staff product training, and sales support materials.

We understand how merchants work. We don't expect you to become ventilation specialists. We support you in holding the right stock, answering the right questions at the counter, and building the long-term installer and contractor relationships that make ventilation a category worth investing in.

Whether you're building a ventilation range from scratch or consolidating supply to improve margins on an existing one, contact the Quiet-Vent trade team to discuss what your branch needs.