We are often being contacted by home owners, who are renovating existing properties, either to extend them or to make them more energy efficient. They install new glazing, add insulation and draft proofing in order to reduce heating costs and cold drafts.
that by upgrading an existing dwelling the risk of black mould triples?
Why is the endeavour to improve a property potentially endangering the health of the occupants? Because often it is overlooked to apply an appropriate ventilation strategy. Whilst living in a drafty dwelling, there seems to be no need to think about fresh air. However if most of the drafts have been blocked off and new air tight windows have been installed, the air infiltration rate is often greatly reduced. Especially in older properties this is more critical than in new builds, as inevitably there will be more cold bridges – parts of the external shell which could not be insulated as much as other parts. These areas have a colder inner surface temperature and attract condensation, which over time leads to mould growth.
Therefore it is important to think about a suitable ventilation strategy when older dwellings are being upgraded, either through new glazing, draft proofing or added insulation.
The approach to a new ventilation strategy is probably as divers as the types of buildings involved:
- For bungalows with a cold loft, it is relatively easy and in-disruptive to install an MVHR system in the loft. Semi-rigid ducting can often be laid underneath the loft insulation, which in many cases will be topped up anyway. Within the rooms only a 130mm hole in the ceiling needs to be drilled for air supply and air extract terminals. External terminals are ideally situated in the gable wall.
- For two storey buildings with a cold loft, the same set-up as for bungalows can be applied. However it will be a bit more disruptive. Ground floor rooms can in some cases be reached through riser pipes in the first floor, situated in-build wardrobes, store rooms or service shafts. For the ground floor a cascade ventilation approach can also be used or a mix of natural and mechanical ventilation.
- For other types of dwelling, part MVHR, de-central MVHR with Cascade Ventilation, dMEV or Positive Input Ventilation (PIV) can be used.
In every case we do look at each case individually to propose a bespoke solution, that will take out excess moisture and pollution and provide enough fresh air for the occupants. MVHR systems have an additional benefit as they actively de-humidify in the cold seasons.
How do we take it from here, if you want to explore the possibilities to ensure good air quality for your property?
- Please do send us an email, describing your situation and your proposals how you want to change your house? Do you have a sketch of your house or could you draw one, showing the number and position of all rooms.
- We will prepare a specification and costing proposal for you.
- If you are happy with this proposal in principle, we can then arrange a free site visit (if you are based in Central Scotland).