Effectively venting all year round


Richard Carter from EnviroVent looks at how installing effective mechanical ventilation systems can reduce the maintenance burden that some housing associations experience in the winter months, and in turn positively impact tenant health

As we approach Autumn, thoughts turn towards planning maintenance programmes and the likely increase in demand as the weather turns colder, and condensation and mould growth becomes a problem in homes once again.

Excess moisture in the home is produced by people breathing, as well as through everyday activities like bathing, cooking, washing and drying out clothes – which can release an average of 18 litres of water vapour per day into the home. During the colder months, indoor air is much warmer and holds more moisture than outdoor air. When warm, humid indoor air comes in contact with windows and cold spots on walls, the moisture cools and forms condensation.

As homes have been upgraded to become increasingly airtight, with double glazing and insulation, humidity cannot escape, leading to condensation forming. If the problem is left, unsightly black mould can be the result, causing damage to walls, curtains and furnishings in the home and also exacerbating health issues such as asthma and respiratory conditions.

Housing providers will be aware that the DHLUC (Department for Levelling Up, Housing and Communities) has published guidance covering damp and mould in rented housing. Known as Awaab’s Law, this guidance is intended to ensure all homes meet the Decent Homes Standard and for any that do not the housing provider must undertake rapid remedial works.

Energy crisis, lower temperatures in homes

The energy crisis and rising fuel bills during last winter saw many tenants turning their heating down, or off completely, causing a problem in some homes.

When a home is heated effectively, the air is warmer, and has a higher capacity to hold moisture. However, when there is a reduction in temperature this can lead to the air holding less moisture and therefore is more likely to form condensation on walls and windows.

Condensation itself may not be a problem, but in cold houses with inadequate ventilation, this can make mould growth more prevalent.

Whole house solution

Many social housing providers are choosing to retrofit Positive Input Ventilation (PIV) systems which work by drawing in fresh, filtered air from outside into a property to gently ventilate the home at a continuous rate from a central position, such as on a landing in a house or a central hallway in a flat or bungalow. PIV systems run quietly and automatically in the background, reducing the overall maintenance costs of a property by protecting the fabric of the building. They prevent the condensation and mould growth that are the cause of so many complaints. To minimise energy usage, many modern PIV units are fitted with an ultra-low watt motor. 

These ventilation systems offer a minimal running cost, especially when compared to everyday household items like TV’s, fridges and kettles – a small price for healthy indoor air quality. They should also eliminate condensation and issues associated with mould growth.

How good ventilation helps

Having a mechanical ventilation system in place means that social housing landlords can have peace of mind that residents are living in homes with good indoor air quality and with less risk of developing or exacerbating respiratory conditions.

An effective ventilation system keeps a home environment healthy as it prevents the build-up of excessive levels of humidity, therefore preventing condensation and mould.  

In the past many homes relied on natural ventilation, such as opening windows or doors, passive air vents and the natural leakage of the building to keep them condensation-free.  However, with modern properties being more airtight, natural ventilation is often insufficient.  

In new homes, updates to Building Regulations Approved Document L and F were introduced in 2022, which require increased levels of air tightness and enhanced ventilation rates in new homes. This has led to a need to review the ventilation systems specified to ensure they are meeting increased airflow rates.

Whole house heat recovery units offer a cost-effective way of meeting Building Regulations Part F requirements, as well as providing low running costs for tenants. These updated Building Regulations are relevant both to new homes and those undergoing refurbishment, making effective ventilation systems increasingly important and mechanical ventilation a compliant solution.

Installing an effective mechanical ventilation system into a property keeps relative humidity under control and delivers improved indoor air quality. Occupants find they often experience an improvement in their symptoms of respiratory conditions such as asthma and other conditions that are known to be exacerbated by poor indoor air quality.  

For a relatively small investment in an effective ventilation system, the result is a long-term solution that reduces the maintenance burden and provides an all-round healthier indoor environment.

Any social housing provider concerned about how condensation and mould growth could affect the fabric of their properties and the health of their tenants, is advised to contact their local ventilation manufacturer. Many offer free surveys that will assess any condensation, damp or mould problems in a property, measure relative humidity levels, identify any underlying problems and make recommendations for a permanent solution.

Richard Carter is regional sales manager at EnviroVent