First of all a very happy new year to all of our clients, business partners, competitors and other readers of this blog.
The new year has started just a few hours ago and since then, the official requirements for the air permeability of new buildings have been lowered to a maximum value of 5m³/m²h, respectively 3m³/m²h in case a mechanical heat recovery ventilation system is installed.
Beside the ongoing confusion about the meaning of the air permeability and the permanent mixing with the air change rate, we believe the new values are still a way too high for an efficient up to date building.
The most European (continent) countries operate with an air change rate of maximum 1.5 air changes per hour for new buildings. Some countries do even have more strict regulations and the Passive House Standard requires a maximum of 0.6 air changes per hour. All values are specified at 50Pa differential pressure.
We know that the air change rate and the air permeability rate of every building vary slightly (or more), depending on the shape of the building. But after doing some analysis of our own air tightness tests and some competitors tests, we´re pretty confident that the deviation between the air change rate and the air permeability is not bigger than a maximum value of 0.5 for the most conventional building shapes. A light house could be completely different, because of the ratio between building volume and building envelope, but we didn´t get a chance for a testing so far.....
Translating our researches into Irish Building Regulations would mean, the maximum value for air permeability should be 2m³/m²h. As always - the lower the value, the better will be the overall energy performance of the building.
Our aim is and will remain, to deliver air tight strategies and materials for a final air change rate of 1.5 ACH and less.
In 2018 we supplied the materials and guided the contractor of the most air tight "Superhome" (deep retrofit scheme) with an air change rate of 1.16ACH/ air permeability of 1.21m³/m²h (official preliminary air tightness test result @50Pa differential pressure).
We also supplied and installed air tight layers for a new build with conventional cavity walls, which achieved an air change rate of 0.58 ACH/ air permeability of 0.81m³/m²h (official preliminary air tightness test result @50Pa differential pressure).
We know that these values are good but not the bottom line and we´re working constantly to optimise details to achieve even better values. Because by the end of the day the small details of the overall air tightness strategy determine the level of air tightness and not the brand of the applied air tightness products.