In November, I shared information about our visit to Living Places Copenhagen, a demonstration home in Denmark addressing energy efficiency, environmental impacts and indoor air quality. Using the project as a ‘living laboratory’, the Living Places team collected data throughout the project and has now published the results. Through my weeklong stay at the house and subsequent review of the data, I found the approach to, and results of, the indoor air quality (IAQ) design particularly informative and inspiring.
Typically, we rely on one of two approaches to IAQ in residential projects: an open window or mechanical ventilation. Opening a window is great but relies on humans to be present and aware of indoor conditions. Mechanical ventilation is also crucial, especially balanced ventilation with heat recovery, but unless you’re actively heating or cooling the building, mechanical ventilation expends unnecessary energy. A third option is the one used in Living Places – operable fenestration (windows or skylights) linked to CO2 sensors to open and close automatically. In that project, the automation is also linked to temperature and humidity sensors for thermal comfort.
CO2 Data Collection and Analysis
The two occupiable homes in Living Places were designed with discreet differences so they could analyze components in isolation. For IAQ, they set up one house to only use the automated skylights, while the other house used a hybrid, adding mechanical fans as well. CO2 levels were measured with calibrated environmental sensors placed in habitable rooms of occupancy. After two months, they found that both homes meet the European Standard (EN 16798-1:2019) for indoor air quality! The European standard is generally equivalent to 750 ppm or below.
Two caveats: First, the homes are designed for effective air movement throughout all spaces, incorporating the stack effect to connect all three floors. Other homes may not have enough connectivity to achieve adequate air movement.
Second, the study was conducted over the summer in Denmark. Air conditioning was not installed or needed, based on the climate and the passive thermal strategies. The home is extremely well insulated and designed for passive heating in the winter, but the homes were not tested for IAQ with thermal comfort demands during winter conditions.
Note that, in California, operable windows and skylights do not replace the code requirement for mechanical ventilation.
Comfortable Personal Experience
For those of us staying in the house, we all felt comfortable and appreciated the indoor conditions. Throughout the day, we would see individual skylights and roof windows open and close. We had remote controllers to override the automation at any time if desired, and the units include weather sensors to automatically close skylights if there is rain. The sensors throughout the house were tied to an app that we could check at any time. Use of the app, along with directly observing the automation, helped build awareness as we ‘tuned in’ to our activity levels, the number of people in the room and changes in temperature, and the collective impact on our comfort.
Using automation for operable skylights and windows can support comfortable temperature and indoor air quality under many conditons. Our experience in the home was for Velux brand of products, but other automatic operation systems are available. One more tool in shared toolbox!
For more information on the project analysis, see “Learnings” on the Velux website.
Questions about optimizing IAQ for your project? Reach out.