Mechanical Engineering · Ventilation Design, Installation and Balancing
MVHR and whole-house mechanical ventilation for airtight London homes
The better a home is built, the less it can breathe on its own. Airtight construction and high levels of insulation are exactly what a modern refurbishment or new build should achieve – but they remove the accidental ventilation older buildings relied on, and trickle vents and bathroom fans cannot replace it. MVHR – Mechanical Ventilation with Heat Recovery – answers that engineered problem with an engineered system: stale, moist air is continuously extracted from kitchens, bathrooms and utility spaces, filtered fresh air is supplied to bedrooms and living rooms, and the heat in the outgoing air is recovered rather than thrown away.
The technology itself is well proven. What separates a system the household never thinks about from one they resent is the engineering around it: duct routes the architecture can absorb, attenuation that keeps the system inaudible in bedrooms, terminals that sit quietly within the ceiling design, and a balancing exercise at the end that makes the installed system match the calculated one. AVC designs, installs, balances and commissions MVHR as a single accountable scope.
Photo location: AVC-EXP-MVH-01
Calm, finished London bedroom or living room with MVHR fully concealed – only a discreet ceiling valve or linear grille visible
Landscape · 16:9 · min 2400 px wide
MVHR – Mechanical Ventilation with Heat Recovery – is a whole-house ventilation system that continuously extracts stale, humid air from wet rooms and supplies filtered fresh air to habitable rooms, transferring heat from the outgoing air stream to the incoming one. AVC Integrations designs, installs, balances and commissions MVHR and mechanical ventilation systems for prime residential projects across London, taking responsibility from ductwork design and acoustic attenuation through to room-by-room air balancing at handover.
The starting point
The problem: airtight homes with an afterthought for air
Ventilation is routinely the last service to be designed and the first to be compromised. When MVHR is squeezed into a scheme late, the symptoms are predictable: duct runs that will not fit the voids left for them, flexible duct crushed around obstructions where rigid duct was drawn, terminals landing wherever the routes allowed rather than where the ceiling design wanted them, and a heat-recovery unit parked somewhere with no acoustic separation and no space to change a filter. The system runs, the occupants hear it, and eventually someone switches it off – at which point an airtight home has no ventilation strategy at all.
Condensation, stale air and poor sleep environments follow, and the remedial options in a finished property are limited and disruptive. None of this is a shortcoming of MVHR as a technology. It is what happens when a system that lives almost entirely inside ceilings, floors and joinery is designed after those elements are fixed.
How AVC works
The AVC approach: designed into the building, proven at the end
We treat ventilation as a spatial design exercise first. Airflow rates are established room by room through calculation, with Building Regulations Part F as the baseline, and those rates drive duct sizing, unit selection and terminal positions. Routes are then resolved with the architect and interior designer while the ceiling strategy is still open – rigid ductwork on planned falls and runs, attenuators positioned where they protect bedrooms, the heat-recovery unit located for both acoustic separation and filter access, and every valve and grille agreed against the decorated ceiling rather than dropped onto it.
Installation is only half of delivery. Every AVC system is balanced at commissioning – each terminal measured and adjusted so the air the design promised is the air each room actually receives – and the results are documented at handover. Because we frequently deliver the wider mechanical and electrical scope, MVHR arrives coordinated with cooling, heating, lighting and joinery instead of competing with them for the same voids.
Photo location: AVC-EXP-MVH-02
MVHR design drawing or BIM model showing supply and extract duct routes, the heat-recovery unit location and attenuators
Landscape · 4:3 · min 1800 px wide
What we deliver
Scope of service
From first strategy conversation to a balanced, documented system, an AVC ventilation appointment typically covers:
System design
- Room-by-room ventilation rate calculations
- Whole-house supply and extract strategy
- Heat-recovery unit selection and location planning
- Filtration strategy for London's urban air
- Acoustic attenuation design for ducts and terminals
- Intake and exhaust positions resolved with the façade and roof design
Ductwork and integration
- Rigid ductwork layouts sized and routed against structure
- BIM coordination with cooling, drainage, lighting and joinery
- Ceiling-void and bulkhead strategy agreed with the architect
- Discreet terminal and grille selection with the interior designer
- Builders' work, penetrations and fire-stopping information
Balancing and commissioning
- Installation by our own engineering teams
- Airflow measurement and balancing at every terminal
- Boost, summer-bypass and control configuration
- Commissioning records and handover documentation
- Filter-change demonstration and a maintenance path for the household
Interfaces, resolved
A system that lives inside the architecture
Almost every component of an MVHR system is concealed, which means almost every component competes for space with something else – structure, cooling, drainage, lighting, joinery. The system succeeds when those negotiations happen on drawings, with the design team, before anything is built.
- Duct routes resolved in the coordinated model before ceiling heights are fixed
- Supply and extract terminals positioned with the lighting and ceiling design, not after it
- Attenuators placed to protect bedrooms and quiet rooms from unit and cross-talk noise
- The heat-recovery unit located for acoustic separation, condensate drainage and filter access
- Intake and exhaust penetrations agreed with the façade, roofing and planning strategy
- Joinery and bulkheads detailed with the interior designer where routes need concealment
- Electrical supplies and controls delivered within the wider AVC electrical package
Photo location: AVC-EXP-MVH-03
Installation detail – rigid MVHR ductwork, acoustic attenuators and the heat-recovery unit neatly installed before ceilings close
Landscape · 4:3 · min 1800 px wide
Where this applies
Project types
Airtight new builds
whole-house ventilation designed alongside the fabric strategy from the outset
Deep refurbishments
MVHR threaded through an existing structure once airtightness works make it necessary
Basement developments
habitable lower-ground spaces that depend entirely on engineered fresh air
Apartments and penthouses
lateral homes where routes, risers and terminal positions must be solved spatially
Delivery
How an MVHR project runs
- 01
Strategy
ventilation approach agreed against the airtightness ambition, layouts and planning context
- 02
Calculation
room-by-room airflow rates established as the basis for every later decision
- 03
Design
unit selection, duct sizing, attenuation and terminal positions developed with the design team
- 04
Coordination
routes, voids and penetrations resolved in the model against structure and other services
- 05
Installation
rigid ductwork, attenuators and the unit installed and pressure-checked before ceilings close
- 06
Balancing
every terminal measured and adjusted so installed airflows match the calculated design
- 07
Handover
controls configured, records issued and filter maintenance demonstrated to the household
Timing
Why early involvement matters
MVHR is the most space-hungry service most residential projects will contain, and the space it needs – continuous duct routes, void depth, a plant position with acoustic separation – is exactly the space that disappears first as a design develops. Brought in early, we reserve those routes while reserving them costs nothing; brought in late, we are trading duct sizes against ceiling heights in rooms that were never meant to have bulkheads.
Early engagement also lets ventilation be designed with the cooling and heating strategy rather than around it, since the same voids, risers and ceilings must carry all three. The best MVHR systems on our projects are the ones nobody on site ever had to improvise.
Placeholder – project evidence
Project example to follow – a genuine AVC whole-house MVHR installation with balancing records and photography, published with the client's permission.
Photo location: AVC-EXP-MVH-04
Completed kitchen or bathroom with extract terminals integrated into the decorated ceiling – the system invisible in use
Landscape · 16:9 · min 1800 px wide
Connected expertise
Related services
Mechanical Engineering
the full mechanical scope – ventilation, cooling and heating as one package
Mechanical Design & Consultancy
design-only ventilation appointments and consultant support
Daikin VRV Air Conditioning
comfort cooling designed alongside the fresh-air strategy
MEP Design, BIM & Coordination
how duct routes are resolved against structure before site
From the knowledge centre
Related engineering guides
MVHR Explained: The Complete Guide to Heat Recovery Ventilation
Modern airtight buildings can't breathe on their own. MVHR delivers continuous fresh, filtered air while recovering up to 90% of the heat you'd otherwise throw away – here's how to get it right.
Read article
Part O Explained: The Overheating Rules Reshaping New Homes in London
The newest part of the Building Regulations is quietly redrawing façades across London. How the simplified method and CIBSE TM59 modelling actually work, why noise and security rules push most urban schemes into dynamic modelling, and where mechanical cooling legitimately fits.
Read article
The Complete Guide to MEP Design for Prime Residential Projects
On a prime home, the engineering has to be invisible, silent and faultless – in half the space a commercial building would allow. This is how experienced MEP designers actually deliver that.
Read articleQuestions, answered
Frequently asked questions
Does MVHR replace air conditioning?+
No – they do different jobs. MVHR supplies fresh, filtered air and recovers heat that would otherwise be lost; it moves modest volumes of air and is not sized to cool a room on a hot day. Comfort cooling remains the job of the air-conditioning system, and on most of our projects the two are designed together so ducts, voids and ceilings serve both without conflict.
Will we hear it running?+
A properly engineered system should be effectively inaudible in bedrooms and living spaces. That outcome is designed, not hoped for: the unit is located away from sensitive rooms, attenuators are placed on the duct runs, duct velocities are kept low through correct sizing, and cross-talk between rooms is treated. Noise complaints almost always trace back to systems where one of those steps was skipped.
How much ceiling void does MVHR need?+
It depends on the duct sizes the airflow calculations demand and on how routes can be shared with other services, which is why we resolve it project by project in the coordinated model. The honest answer is that MVHR needs more concealed space than any other domestic service – and that securing routes early is the difference between clean ceilings and improvised bulkheads.
What maintenance does an MVHR system need?+
The routine task is filter replacement, at intervals that depend on local air quality and how the system is used. Filters also matter more in London than in most places, since they are what stands between urban air and the bedrooms. We position units so filters are genuinely accessible, demonstrate the change at handover, and can arrange ongoing maintenance as part of aftercare.
Can MVHR be retrofitted into an existing house?+
Often, yes – but feasibility is a routing question, not a product question. A deep refurbishment that opens floors and ceilings is usually a good opportunity; a decorated, occupied house rarely is. We assess the structure, void depths and possible unit locations early and give a straight answer, including where a partial or alternative ventilation strategy would serve the project better.
Why does balancing matter so much?+
Because an unbalanced system quietly fails at its only job. Without measurement and adjustment, some rooms are over-ventilated and noisy while others are starved of fresh air, and the heat-recovery performance the design assumed is never achieved in practice. Balancing every terminal against the calculated rates – and recording the results – is what turns an installation into a working system.
Why does an airtight home need mechanical ventilation at all?+
Because the leaks that once ventilated buildings by accident are precisely what modern construction is designed to eliminate. Once a home is airtight, moisture from cooking, bathing and simply occupying the space has nowhere to go, and condensation, stuffiness and poor air quality follow. Engineered ventilation is the necessary partner of an engineered fabric – one does not work well without the other.
Can the grilles and valves be discreet?+
Yes, and on our projects they must be. Terminal positions are agreed with the interior designer against the ceiling design, linear grilles or minimal valves are selected to suit each room, and finishes are chosen to sit quietly within the decoration. The aim is a system the household feels in the air quality and never notices on the ceiling.
Start the conversation
Plan Your Ventilation Commissioning
Share your drawings, programme or brief and our engineering team will come back with a considered view of scope and approach – and the decisions worth making while they are still cheap to make.