A continuous struggle in building ventilation design is achieving a balance between the amount of fresh air introduced to the building to maintain occupants' health and the associated energy bill with conditioning/filtering this air from target pollutants.
In a Clean Air Study conducted by NASA in 1989, the primary study researcher Dr B. C. Wolverton; concluded that certain species, such as English ivy, Spider plant, Peace lily, Chinese evergreen, Bamboo palm and others; when installed indoor with a minimum quantity of 8 plants/person can work as a natural "living machines" that scrubs indoor carcinogenic air pollutants as well as bringing down indoor Carbon Dioxide levels.
This conclusion can be a game-changer for indoor air quality in buildings as well as mechanical air filtration systems' design norms and associated energy needs. The coupling of this biophilic design element "living machines" using the right plant types and density, with smart active control on filtration system (utilizing real-time pollutants' monitors for filtration demand control) can result in less need for fresh air; reducing associated energy demand; while maintaining a healthier indoor air quality than the surrounding outdoor air.
This remarkable result has been realized by "Lend-lease China" a few years back when they decided to implement this strategy in their China HQ by using the right plant species, higher densities of indoor plants (above 8 plants/person threshold recommended by the study), and deploying innovative air filtration control using real-time pollutant monitors. The resulting pollutant levels, including Carbon Dioxide levels, were stunning for a country that is ranked one of the highest polluted spots on earth. The indoor Carbon Dioxide levels were significantly dropped to around 280 ppm, which is considerably lower than the global Carbon Dioxide levels recorded currently, i.e. 405 ppm.
So how would these contradicting goals (enhancing indoor air quality while reducing energy demand) reconcile with each other!
The need for introducing fresh air to a building is primarily driven by maintaining a healthy level of Carbon Dioxide (below 600 ppm is preferable for high performing buildings) to avoid what is commonly known as "Sick Building Syndrome". Outdoor air quality and pollution levels vary from place to place on earth.
Additionally, occupants' activities and usage of finishes & furnishings are continuously disseminating various pollutants; such as Carbon Dioxide, Particulate Matters (PM), TVOC, ..etc, into the indoor environment.
This brings up a bi-fold challenge to the Mechanical designers to devise reliable and responsive systems capable of maintaining safe steady-state levels of target indoor pollutants over the building lifetime, while efficiently conditioning and filtering fresh air admitted to the building with the least energy requirements.
Relying on mechanical systems only to overcome these two challenges will come at significant energy and operational costs that will render any investment in this regard unfeasible.
This is where the innovation and out-of-the-box creativity of both Mechanical and Interior designers will come into play to offer a solution that can realize this objective of a safer/healthier indoor air at reduced energy and operational costs.
The integration of "Living Machines" (Biophilic Interior Design Aspect) into the overall design strategy, will passively (at ZERO energy cost) reduce target indoor pollutants' levels, giving way for reduced fresh air building demand and associated mechanical systems' energy bill.
Furthermore, the reduced fresh air quantities shall allow for more attractive investment opportunities in additional add-on features, including:
- Additional recirculated in-ceiling air filtration (which normally constitutes somewhere between 80-90% of total supply air inside a building).
- Enhanced real-time monitoring and control on filtration systems based on real-time pollutants' levels.
The overall outcome of this integrated strategy shall result in a win-win situation for all. Reduced mechanical systems cost, enhanced indoor air quality and improved biophilic interior design along with improved occupant satisfaction.
In today's industrialized world, the current imminent climate challenge necessitates swift migration from "business-As-Usual" buildings' design norms and approaches, towards more innovative and out-of-the-box tactics offering more aggressive confrontation to various building challenges, with occupants' health placed on the top of this challenges' list. Design tactics focused on active monitoring and control of indoor target pollutants (i.e.; Carbon Dioxide, PM, TVOC) using a combination of passive and real-time active measures, should be pushed forward in new building designs, as well as major retrofits to insure healthier built environments as well as incorporate the built environments as climate challenge mitigation frontiers supporting the current global combat against climate change.