An important founding concept of the Passivhaus standard is maintaining a high level of thermal comfort. Simply stated, the closer interior surface temperatures are to the interior ambient air temperature, the warmer occupants feel (it all stems from the concept of mean radiant temperature). The Passivhaus standard demands a maximum surface temperature difference of 4.2°K (7.56° F) between interior set point and transparent surfaces. This is one reason why we utilize highly thermally resistive, high performance windows in our designs. Couple this with a movement towards point source heating/cooling (i.e. providing heating/cooling from a minimal amount of ‘point’ sources) and the importance of a high performance envelope is exemplified.
For large scale commercial Passivhaus projects the importance of a high performance glazing can be even more important as the North American architectural vernacular for commercial buildings shows the general trend of larger transparent to opaque ratios versus the standard residential dwelling. Add on the fact that the skin in large scale commercial buildings is typically further away from the core of the building and the importance of windows to maintain the thermal comfort criterion is highlighted.
In many jurisdictions, local building codes do not allow wood or fiberglass framing in windows used for occupancies typical of large scale commercial projects; these are typical frame materials for high performance windows in both North America and Europe. As such, the importance of understanding windows and the complex heat transfer mechanisms becomes paramount in order to achieve the Passivhaus standard for large scale commercial buildings.
We have in-house expertise in analyzing heat transfer mechanisms, specifying and detailing installation of high performance windows systems for large scale commercial Passivhaus buildings. If you would like more information on this, please do hesitate to reach out to us.