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Indoor Air Quality (IAQ) vs Energy Efficiency (EE): Is it a Zero-Sum-Game?

Indoor Air Quality vs Energy Efficiency

IAQ & EE: Two crucial problems of modern society

If the pandemic taught us anything, we should care more about where we live. Moreover, recent studies show that Europeans spend 90% of their time indoors in homes, offices and schools (EVIA, 2022). Therefore, the building industry is vital for our society, but right now, it has two main problems to reconcile. First, it is known that buildings in the EU account for 40% of the energy consumption and for 36% of the overall greenhouse gas emissions (European Commission, 2020; EVIA, 2022). So, since the first energetic crisis in the 1970s, the people involved in this industry tried to find out a way to reduce energy costs and, furthermore, the fight against climate change requires reducing emissions. The answer to both problems has been to seal up buildings, reducing ventilation, in order to make them energy efficient, but this was among the causes of another problem: the so-called sick buildings (Hailstone, 2022).

Sick buildings are those where the IAQ is poor and environmental conditions may affect human health. Even if outdoor air quality receives much attention, IAQ has been forgotten for many years. In fact, it has been sacrificed to EE many times due to the fact that it has been related to high energy consumption because of its need for heating and air conditioning systems (Hailstone, 2022). Nevertheless, exposition to indoor contaminants can cause from minor problems – like coughing, sneezing, fatigue, and headaches – to serious health issues – like allergic and asthma symptoms, lung cancer, chronic obstructive pulmonary disease, airborne respiratory infections, and cardiovascular diseases (EPA, 2003; EVIA, 2022). In addition, the IAQ in schools and offices is crucial for productivity, as in a ventilated environment, students perform 15% better, and workers are at least 10% more productive.

Multiple factors can produce an unhealthy indoor environment: first of all, indoor pollutants, like mould, dust, human and animal waste, or even building materials, furniture and equipment, or cleaning products; but also outdoor pollutants, coming from outside the building through the ventilation system (EPA, 2003). Due to its concentration, indoor air can be twice or even five times more polluted than outdoor air (EVIA, 2022). Hence, regulating the three fundamentals of IAQ is important: outdoor airflow, temperature and humidity. The two latter are vital to prevent chemical release and indoor pollutants increase; the former is the best way to keep a healthy closed environment, even if it can be counterproductive when the outside air is not clean (EPA, 2003; EVIA, 2022; Hailstone, 2022).

 

Are IAQ and EE two competing goods?

Reding the previous section and looking at what has been done in the past, it could seem that one between IAQ and EE must be sacrificed, prioritising the other, but it has been proved that it is not true, and the Covid-19 pandemic gave us a huge opportunity that we must not waste.

Even though there is often tension between improving IAQ and making a building as efficient as possible, an EPA study showed that by adopting the same energy cost-reducing measures, the savings were between 22 and 41% if improving IAQ adjustments were not made and between 19% and 37% if they were (EPA, 2003; Hailstone, 2022). So, it is clear that the price spent for a healthier environment is low and completely worth it. Anyway, every EE upgrade has a different impact on IAQ. For example, as stated already, the attention on EE in the building industry caused a reduction in ventilation rates, affecting the indoors. Other cases when EE solutions degrade IAQ are variable air volume (VAV) systems when there is no outdoor air fixed standard and the usage of ozone air purifiers that are actually bad for the internal environment (EPA, 2003). There are then upgrades that have a negligible effect on IAQ – like chiller/boiler system ones (EPA, 2003). Nevertheless, there are also EE solutions that can improve IAQ, for instance, Tuning-up the HVAC (Heating, Ventilation & Air Conditioning) system, and the best solution, according to many experts, is the energy recovery ventilation (ERV) technology or even recycling the air already in the building (EPA, 2003; Hailstone, 2022). While the ERV technology works using the latent energy in the indoor air flowing outside to condition the outdoor air inflowing, air recycling uses vents and air cleaning and filtration technologies to be able to reuse the air already inside the building without the need for conditioning it or the risk of introducing outdoor pollutants (EPA, 2003; Hailstone, 2022).

Another issue with the reconciliation between IAQ and EE is that we do not have explicit, coherent regulations, standards, and building codes that, among other things, can define what we mean when we talk about a “good IAQ” (EVIA, 2022; Hailstone, 2022). For example, CO2 has been used for years as the main parameter to evaluate IAQ, while it is not as reliable as thought. A good starting point could be implementing indoor environmental quality-related requirements in building-related policies such as the Energy Performance of Buildings Directive (EPBD) (EVIA, 2022; Hailstone, 2022). So, many organisations are pushing on the EU legislator to better regulate this field with a holistic approach; among them, there is the EDIAQI Project. Within the Horizon Europe framework, EDIAQI aims to study the sources, routes of exposure, and health effects of indoor air pollution through measurements and monitoring in European cities. A better understanding of indoor air contamination will be helpful to support policymakers in reviewing standards and regulatory measures, with the final goal of providing science-based evidence to support the Zero-Pollution Action Plan of the European Green Deal (EDIAQI, 2023).

To conclude, IAQ and EE can coexist, as explained above, and with the Covid-19 pandemic shredding light on the importance of a healthy environment inside our buildings, it is now the right moment to implement the proper measures and not waste a long-waited opportunity to improve lives.

 

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