Latest Trends in Pollutant Accumulations at Threatening Levels in Energy-Efficient Residential Buildings with and without Mechanical Ventilation: A Review

Abstract

Improving the energy efficiency of buildings is a major target in developed countries toward decreasing their energy consumption and CO2 emissions. To meet this target, a large number of countries have established energy codes that require buildings to be airtight. While such a retrofitting approach has improved health outcomes in areas with heavy traffic, it has worsened the health outcomes in Nordic countries and increased the risk of lung cancer in areas with high levels of radon emissions. This review highlights the importance of adapting the characteristics of energy-efficient residential buildings to the location, age, and health of inhabitants to guarantee healthy indoor pollutant levels. The implementation of mechanical ventilation in new energy-efficient buildings has solved some of these problems; however, for others, a decrease in the level of outdoor pollutants was still required in order to achieve a good indoor air quality. A good balance between the air exchange rate and the air humidity level (adapted to the location) is key to ensuring that exposure to the various pollutants that accumulate inside energy-efficient buildings is low enough to avoid affecting inhabitants′ health. Evidence of the protective effect of mechanical ventilation should be sought in dwellings where natural ventilation allows pollutants to accumulate to threatening levels. More studies should be carried out in African and Asian countries, which, due to their rapid urbanization, use massive volumes of unproven/unrated building materials for fast-track construction, which are frequent sources of formaldehyde and VOC emissions.

Season, Vegetation Proximity and Building Age Shape the Indoor Fungal Communities’ Composition at City-Scale

“…These differences have been associated with a different composition of fungal community [ 66 , 67 ]. Thus, older properties have been shown to need more maintenance to prevent the ingress of water [ 68 ], while dwellings constructed after 1975 are too airtight, which favors the accumulation of humidity in indoor air [ 69 ]. Nevertheless, the period of building construction is an indicator that has rarely been considered in recent metabarcoding studies [ 25 ].…”

Harm from Residential Indoor Air Contaminants

“…A study of 70 Californian homes is used as a reference for median PM 2.5 , formaldehyde, and nitrogen dioxide concentrations at 5, 23, and 9 μg/m 3 , respectively . Ozone and radon were not measured in these dwellings, and so guideline values of 40 μg/m 3 and 100 Bq/m 3 are used as reference concentrations, respectively . Furthermore, they are likely to contribute only a small proportion of the total harm.…”

“…125 Ozone and radon were not measured in these dwellings, and so guideline values of 40 μg/ m 3 and 100 Bq/m 3 are used as reference concentrations, respectively. 130 Furthermore, they are likely to contribute only a small proportion of the total harm. PM 10−2.5 is not considered here because a guideline value does not exist.…”

Mechanisms of Diffusion of Radon in Buildings and Mitigation Techniques

“…Such interventions are typically carried out by adding internal or external thermal insulation layers and replacing window frames with more thermally efficient ones. Whether such interventions are implemented together with a proper mechanical ventilation system or not, they strongly reduce the permeability of the building envelope, with possible repercussions on indoor air quality and a potential increase in exposure to radon [108,[119][120][121][122][123][124][125][126].…”

“…cient ones. Whether such interventions are implemented together with a proper mec ical ventilation system or not, they strongly reduce the permeability of the building e lope, with possible repercussions on indoor air quality and a potential increase in e sure to radon [108,[119][120][121][122][123][124][125][126].…”