Ventilation for New Builds Done Right First Time

A new home can look perfect on handover day and still develop condensation in the bedrooms, lingering bathroom moisture and mould behind furniture within its first winter. The reason is often simple: ventilation for new builds was treated as a late-stage item rather than a core part of the building design. In an airtight property, fresh air does not arrive by accident. It must be planned, supplied and tested.

For homeowners, builders and developers, the aim is not merely to fit fans and satisfy a drawing. It is to create a home that feels fresh, protects the building fabric and gives occupants a healthier place to live. That means selecting the right system early, coordinating it with insulation and airtightness work, and commissioning it properly before completion.

Why new homes need a planned ventilation strategy

Modern construction is designed to reduce unwanted heat loss. Better insulation, sealed windows and improved airtightness are all positive steps for comfort and energy performance. However, they also reduce the natural background air movement that older, draughtier homes relied on.

People create moisture every day through showering, cooking, drying clothes and even breathing while asleep. Without an effective route for moist, stale air to leave the property, humidity builds up. That can lead to condensation on colder surfaces, mould growth, damaged finishes and poor indoor air quality.

Opening windows helps at times, but it is not a reliable ventilation strategy. Occupants may be away, asleep, concerned about noise or security, or simply reluctant to lose heat during colder weather. A designed system works consistently in the background, rather than relying on habits that vary from household to household.

There is also a compliance requirement. New dwellings in Ireland must meet the ventilation provisions of Technical Guidance Document F, TGD F-2022, alongside the wider Irish Building Regulations. The installed system must deliver the required airflow in practice, not only on paper.

Choose the system before services are fixed

The best ventilation choice depends on the layout, build specification, occupancy and budget. Waiting until plastering or second fix limits the options and can create avoidable compromises with duct routes, electrical supplies and ceiling space.

Centralised heat recovery ventilation

A centralised mechanical ventilation with heat recovery system, often called MVHR, is frequently suited to new-build houses with a good airtightness standard. It continuously extracts stale, moist air from wet rooms such as bathrooms, utility rooms and kitchens, while supplying filtered fresh air to living rooms and bedrooms. Heat from extracted air is recovered to temper the incoming air.

This can offer excellent whole-house air quality and help reduce heating demand. The trade-off is that centralised systems need careful early design. Ductwork must have sensible routes, the unit needs an accessible location for maintenance, and the system requires proper balancing. Poor duct design or rushed installation can introduce noise, restrict airflow and undermine performance.

MVHR is not automatically the right choice for every project. A compact dwelling, a phased construction project or a property with limited service voids may be better served by another approach. What matters is matching the system to the building, not forcing the building around a preferred product.

Single-room heat recovery ventilation

Single-room heat recovery units provide local extraction and supply ventilation through an external wall. They can be a practical solution for individual rooms, smaller homes and projects where extensive ductwork is unsuitable. They are also valuable where a targeted room needs additional ventilation without disrupting the whole property.

For new builds, these units need to be considered alongside room use, wall construction, external appearance and access for servicing. Core drilling should be completed accurately and at the right construction stage, with suitable weatherproofing and internal finishing planned around the installation.

Intermittent extract ventilation

Extractor fans remain a common option for kitchens, bathrooms, WCs and utility rooms. They can be effective when selected for the correct duty, ducted properly to the outside and controlled appropriately. A fan that is undersized, connected to long flexible ducting or allowed to terminate poorly will not deliver the airflow it was chosen to provide.

Extract-only systems also require planned make-up air. If air cannot enter the dwelling in a controlled way, the system may struggle to extract at its design rate. Trickle ventilators, background ventilators and correctly designed air paths between rooms all have a role, depending on the selected compliance approach.

Design for airflow, not just equipment

Ventilation is a system, not a collection of separate products. The performance of a high-quality fan or heat recovery unit can be lost through poor ducting, restrictive grilles, excessive bends or inadequate transfer paths between rooms.

Wet rooms need effective extraction at source. Habitable rooms need a reliable supply of fresh air. Air must then be able to travel through the dwelling towards extract points, usually via gaps beneath internal doors or purpose-designed transfer grilles. Blocking that path with tightly sealed doors can reduce the system’s effectiveness.

Ductwork deserves particular attention. Keep runs short and direct where possible, size ducts correctly and avoid unnecessary bends. Rigid ductwork is often preferable for main runs because it offers lower resistance and is easier to clean than loosely installed flexible ducting. Where flexible duct is needed, it should be kept taut and as short as practical.

Kitchen extract needs a separate decision. A cooker hood that recirculates air may improve comfort during cooking, but it does not remove moisture and pollutants from the home. A ducted cooker hood removes air externally, yet its design must be coordinated with the overall ventilation strategy and airtightness requirements. It should never be assumed that one appliance replaces the need for compliant whole-dwelling ventilation.

Commissioning is where compliance becomes real

A ventilation design may look correct, but installation variables change results. Duct joints can leak, terminals can be adjusted incorrectly, filters may be obstructed by construction dust and fans may be set to unsuitable speeds. That is why commissioning is essential.

Commissioning involves measuring airflow at terminals, balancing the system and adjusting it to meet the required rates. The final readings should be recorded in a clear report, with certification provided for the project file. This gives builders, developers and homeowners evidence that the system has been tested rather than simply switched on.

For larger projects, professional design and commissioning also reduce handover risk. Problems are identified before residents move in, when access is straightforward and corrective work is less costly. It is far better to resolve a poor airflow reading at completion than to return months later to investigate mould complaints.

PureAir Solution provides ventilation supply, installation, airflow testing, balancing and certification across Ireland, helping projects move from an appropriate system choice to documented compliance.

Do not overlook the handover and maintenance plan

Even a correctly commissioned system needs occupants to understand the basics. Homeowners should know where controls are, when boost settings are useful and how often filters need checking or replacing. They should also understand that ventilation systems are designed to run. Turning them off to save electricity can allow humidity and pollutants to build up again.

Installers and developers should leave clear operating information, commissioning records and maintenance guidance. Access panels and service areas must remain reachable after fit-out. A heat recovery unit hidden behind fixed joinery, or a fan with no practical route for cleaning, creates future problems that could have been avoided during design.

Landlords and property managers have an additional responsibility to keep systems maintained between tenancies. A blocked filter, damaged external grille or failed fan can quickly affect comfort and moisture control, particularly in occupied flats with limited opportunities for window ventilation.

Build clean air into the programme

Ventilation should be discussed alongside foundations, insulation, windows, plumbing and electrics – not after the ceilings are closed. Early coordination creates room for efficient duct routes, appropriate unit locations and professional installation. It also makes it easier to protect equipment from construction dust and damage before final commissioning.

A good new build should feel warm without feeling stuffy, and dry without being difficult to heat. Give ventilation the same attention as any other essential building service, and the result is a healthier home that is ready for real life from the first day the keys are handed over.