Humidity control makes a retrofit home

When one considers the retrofit of a house, more often than not, there is a focus centred around the reduction of energy required to heat up the house. Yet the implementation of humidity control is just as important.

PAS2035 has a fabric first methodology. Aiming for airtightness within the property and the installation of energy efficiency measures such as external wall insulation. It is important to understand that traditional fabric elements do offer some degree of moisture movement. However, most energy efficiency measures reduce this movement so there is still a need for some form of mechanical ventilation to offer humidity control.

Often described as having ‘permeability’ or ‘breathability’ traditional fabric elements only offer slight humidity control as a perk rather than the main function.

Having humidity control considered throughout the property can have a hugely beneficial impact on the occupants. From improving health and wellbeing to ensuring the longevity of the property, humidity control is vital for retrofit success.

See the chart below, which shows the optimum RH level of 35% to 65% and the factor which present outside of these parameters:

Credit: Retrofit Academy

The easiest way to see this is through the extremities of how low and high humidity levels can impact.

For example, if within the dwelling, there is a high level of humidity, it encourages mould and mildew growth. The excess moisture can have a disastrous effect upon the building’s fabric, rotting through vital components. Condensation forming on cold surfaces can become a safety hazard too.

On the other end of the spectrum, low levels of humidity within the dwelling can directly affect the occupant’s thermal comfort.

Low humidity levels within a property can lead to health implications. Not only will occupants feel cold, but it can also lead to respiratory and skin illnesses.

As mentioned earlier, with a retrofit project promoting airtightness, there must be a form of ventilation that will allow control over the humidity levels within the property. This can be done and is most commonly deployed in the form of an MVHR.

The term MVHR is an abbreviation for (mechanical ventilation with heat recovery). MVHR allows you to control humidity and air shifts all day long without losing a lot of heat energy.

This works by extracting warm, moist atmospheric air from the home to extract the heat and then expels the air outside through a heat exchanger. It takes cooler air from the outside and uses the heat from the heat exchanger to warm the fresh air that comes in before it can be delivered around the house.

When completing a retrofit project upon a home, consideration of humidity control is a must. Ensuring a house is truly a home, a place to relax and be comfortable.