Do Green Buildings Have Better Indoor Climate ?

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CIVIL-212 Course - 2019-2020

Authors: Bachmann Lise, Blanc Sarah, Dubien Victor, Preto Anne-Valérie

Green houses are growing in popularity. The promise of a home in symbiosis with the environment which consumes little energy is a dream. However, are there harmful aspects of these houses? Is the indoor climate really better for humans?

It seems important to define what a green building means. The most common concepts that come up in different definitions are the following;

  • Good insulation

  • Reduced energy consumption

  • Durable (choice of materials)

  • Environmentally friendly (renewable energy)

These factors are taken into account throughout the construction, maintenance and use of the dwelling.

There are various labels to control the market for “green houses”. In Switzerland, the label recognised by the Confederation is the Minergie label3. It emphasises quality and energy efficiency and adds value to a house. Few tests are required to certify a Minergie home. It is mainly necessary to conclude an airtightness test to guarantee low energy losses.15

However, this insulation requires a review of the ventilation to ensure sufficient air flow. The labels often focus on the technical aspect of the building design with few criteria concerning the indoor climate.

This raises a number of questions: 

How can we save as much (heating) energy by ensuring a good indoor climate?
Are there any disadvantages to focusing so much on the materials used?
Is the ventilation system sufficiently redesigned to guarantee good air exchange?
Would components (formaldehyde, radon) not stagnate because of the high airtightness?

EFFECT ON HUMANS AND INFLUENCING FACTORS IN BUILDING

After defining what a green building is and what are the positive and/or negative impacts of these constructions on the environment. Are all these aspects beneficial to humans? Since people spend an average of 90%17 of their time indoors, IAQ is very important. However, little credit is given to IAQ when it comes to assessing a building’s compliance with green building standards (only 3 to 11 per cent)17. Therefore, in this section the impact of green building standards on indoor air quality will be discussed. 

Firstly, there is very little research on the subject that has affirmed or denied the beneficial effects of this type of construction. It is currently difficult to quantify the benefits of these green standards. One study17 compared two hospitals. One was a green hospital and the other a usual one. The conclusion of this study showed that the mortality rate, blood infections and drug consumption were lower in patients who were hospitalised in green buildings than the one hospitalised in usual buildings. However, evidence of these types of studies are generally weak. In the afforded mentioned study, it is difficult to correlate the results of the green hospital with the health of patients. Indeed, there are too many uncontrolled variables – other than the green architectural properties of the building – which can affect a patient’s health (skills of health care teams for example). 

In green buildings, a special effort is made in the choice of materials:  labels recommend using recycled materials (waste-based) which often contain more heavy metals and can re-emit pollutants (VOCs) that have been adsorbed on their surfaces. These can then harm the health of the occupants. 

As mentioned above, green buildings are very well insulated, which implies reinforced ventilation. In some cases, this ventilation breaks the chemical equilibrium at the surface of the materials. This leads to a release of pollutants into the indoor air. 1

In order to refresh the indoor air, the occupants are led to apply the policy of “freecooling”. Although effective, this practice allows an accumulation of outdoor pollutants indoor which can lead to a decrease in indoor air quality. 

In order to limit the intrusion of outdoor pollutants indoors, air purification systems have been developed. Unfortunately, according to few researches, these purifiers are not able to eliminate all pollutants. They may even promote the creation of new pollutants (more harmful than those eliminated) through the precipitation of any compounds. 

As mentioned above, green buildings are often built near highly urbanized areas (public transportation, housing density, etc…). In these areas, outdoor air pollution is even higher than in the outskirts. Thus, it is easy to highlight the intrusion, inside these buildings, of pollutants that are harmful to the organism.  

These examples show how important it is to rethink, reinvent, some of the green building standards and put health and indoor air quality back at the centre of the green building development process. Therefore, it could be wise to develop a paragraph on the measures to be taken in order to improve the situation.

REMEDIAL ACTIONS – WHAT CAN WE DO TO IMPROVE THE SITUATION ?

In order to ensure both human health and comfort in what were defined as green buildings, there are different  available options. As said above, the first and main emitter of VOCs in buildings are construction materials (wood composites, floorings, walls, paints,…) so the best option would be to use low-emitting materials such as raw (actually lightly treated) wood, or natural pigmentations for walls instead of paint. 

Another viable solution is to use low-emitting windows, which significantly reduce the amount of UVs and IRs without impacting the amount of light entering the room. This type of window is also designed to minimise air leakage, enhancing  thermal comfort control. 10



Green walls could be seen as a solution for replacing usual building materials in walls. The outside part of the wall is composed of plants which have their roots either in water or soil. The outside air is “cleaned” by the plants and thanks to a fan system, reinjected inside.



However, this solution is yet to be assessed, because the NO2 rejection level  could be harmful to humans14. If this option was viable, it would be a great improvement in both green buildings and indoor climate terms. 

Finally, it may be good to remember that a lot of VOCs also come from our own lifestyle and product usage (cleaning chemicals,…) so there is no easier way than not using them to avoid them (valid for any building).

CONCLUSION

In conclusion, this work showed how difficult it is to link a green building with a good indoor climate (see Hospital study). Some actions that may appear to be beneficial to energy saving (or other) actually have deleterious effects on the quality of indoor air. 

There are several solutions to respond to these harmful effects, but it seems that a collective awareness of the population on the importance of indoor climate would be a good start. The development of a label that takes both aspects into account would also be an approach to be explored (Eco Label) .

 

References

  1. Babich, Francesco, Ingrid Demanega, Francesca Avella, et Annamaria Belleri. « Low Polluting Building Materials and Ventilation for Good Air Quality in Residential Buildings: A Cost–Benefit Study ». Atmosphere 11, no 1 (janvier 2020): 102. https://doi.org/10.3390/atmos11010102.

  2. Conceição, Eusébio, João Gomes, et Hazim Awbi. « Influence of the Airflow in a Solar Passive Building on the Indoor Air Quality and Thermal Comfort Levels ». Atmosphere 10, no 12 (décembre 2019): 766. https://doi.org/10.3390/atmos10120766.

  3. MINERGIE Schweiz. « En bref ». Consulté le 31 octobre 2020. https://www.minergie.ch/fr/a-propos-de-minergie/en-bref/.

  4. Geng, Yang, Borong Lin, et Yingxin Zhu. « Comparative Study on Indoor Environmental Quality of Green Office Buildings with Different Levels of Energy Use Intensity ». Building and Environment 168 (15 janvier 2020): 106482. https://doi.org/10.1016/j.buildenv.2019.106482.

  5. « How green buildings can help fight climate change | U.S. Green Building Council ». Consulté le 31 octobre 2020. https://www.usgbc.org/articles/how-green-buildings-can-help-fight-climate-change.

  6. « LEED and the Future of Green Building | Greenbiz ». Consulté le 21 novembre 2020. https://www.greenbiz.com/article/leed-and-future-green-building.

  7. « LEED rating system | U.S. Green Building Council ». Consulté le 21 novembre 2020. https://www.usgbc.org/leed.

  8. Licina, Dusan. « Special Issue Editorial: Green Buildings and Indoor Air Quality ». Atmosphere 11, no 5 (mai 2020): 441. https://doi.org/10.3390/atmos11050441.

  9. Licina, Dusan, Seema Bhangar, et Chris Pyke. « Occupant health & well-being in green buildings: Trends and Future Directions ». ASHRAE Journal, 30 avril 2019. http://infoscience.epfl.ch/record/265917.

  10. Sutori. « Low Emitting Materials », 2 mars 2020. https://www.sutori.com/story/low-emitting-materials–qvmCGFxKX7xpvDaBefd9esbf.

  11. MINERGIE Schweiz. « Modèles de rénovation Minergie ». Consulté le 31 octobre 2020. https://www.minergie.ch/fr/a-propos-de-minergie/renover/modeles-de-renovation-minergie/.

  12. Newsham, Guy, Benjamin Birt, Chantal Arsenault, Alexandra Thompson, Jennifer Veitch, Sandra Mancini, Anca Galasiu, Bradford Gover, Iain Macdonald, et Gregory Burns. « Do green buildings have better indoor environments? New evidence ». Building Research and Information 41 (13 mai 2013): 415‑34. https://doi.org/10.1080/09613218.2013.789951.

  13. Oldham, Emily, et Hyojin Kim. « IEQ Field Investigation in High-Performance, Urban Elementary Schools ». Atmosphere 11, no 1 (janvier 2020): 81. https://doi.org/10.3390/atmos11010081.

  14. Pettit, Thomas, Peter J. Irga, Nicholas C. Surawski, et Fraser R. Torpy. « An Assessment of the Suitability of Active Green Walls for NO2 Reduction in Green Buildings Using a Closed-Loop Flow Reactor ». Atmosphere 10, no 12 (décembre 2019): 801. https://doi.org/10.3390/atmos10120801.

  15. MINERGIE Schweiz. « Procédure ». Consulté le 31 octobre 2020. https://www.minergie.ch/fr/certifier/procedure/.

  16. « Standard 189.1 ». Consulté le 7 novembre 2020. https://www.ashrae.org/technical-resources/bookstore/standard-189-1.

  17. Steinemann, Anne, Pawel Wargocki, et Behzad Rismanchi. « Ten Questions Concerning Green Buildings and Indoor Air Quality ». Building and Environment 112 (1 février 2017): 351‑58. https://doi.org/10.1016/j.buildenv.2016.11.010.

  18. Trocquet, Claire, Pierre Bernhardt, Maud Guglielmino, Isabelle Malandain, Céline Liaud, Stéphanette Englaro, et Stéphane Le Calvé. « Near Real-Time Monitoring of Formaldehyde in a Low-Energy School Building ». Atmosphere 10, no 12 (décembre 2019): 763. https://doi.org/10.3390/atmos10120763.

  19. Yang, Shen, Joëlle Goyette Pernot, Corinne Hager Jörin, Hélène Niculita-Hirzel, Vincent Perret, et Dusan Licina. « Radon Investigation in 650 Energy Efficient Dwellings in Western Switzerland: Impact of Energy Renovation and Building Characteristics ». Atmosphere 10, no 12 (décembre 2019): 777. https://doi.org/10.3390/atmos10120777.

  20. Yang, Shen, Joëlle Goyette Pernot, Corinne Hager Jörin, Hélène Niculita-Hirzel, Vincent Perret, et Dusan Licina. « Energy, Indoor Air Quality, Occupant Behavior, Self-Reported Symptoms and Satisfaction in Energy-Efficient Dwellings in Switzerland ». Building and Environment 171 (15 mars 2020): 106618. https://doi.org/10.1016/j.buildenv.2019.106618.

  21. Yang, Shen, Vincent Perret, Corinne Hager Jorin, Helene Niculita-Hirzel, Joelle Goyette Pernot, et Dusan Licina. « Volatile organic compounds in 169 energy-efficient dwellings in Switzerland ». Indoor Air, 13 avril 2020. https://doi.org/10.1111/ina.12667.