{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,2]],"date-time":"2026-06-02T04:51:32Z","timestamp":1780375892709,"version":"3.54.1"},"reference-count":28,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2022,12,2]],"date-time":"2022-12-02T00:00:00Z","timestamp":1669939200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Spanish National Research Agency (Agencia Estatal de Investigaci\u00f3n)","award":["PID2019-105046RB-I00"],"award-info":[{"award-number":["PID2019-105046RB-I00"]}]},{"name":"Spanish National Research Agency (Agencia Estatal de Investigaci\u00f3n)","award":["ICTS-2017-03-CIEMAT-04"],"award-info":[{"award-number":["ICTS-2017-03-CIEMAT-04"]}]},{"name":"Spanish Ministry of Economy, Industry, and Competitiveness","award":["PID2019-105046RB-I00"],"award-info":[{"award-number":["PID2019-105046RB-I00"]}]},{"name":"Spanish Ministry of Economy, Industry, and Competitiveness","award":["ICTS-2017-03-CIEMAT-04"],"award-info":[{"award-number":["ICTS-2017-03-CIEMAT-04"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The measurement of the CO2 concentration has a wide range of applications. Traditionally, it has been used to assess air quality, with other applications linked to the experimental assessment of occupancy patterns and air renewal rates. More recently, the worldwide dissemination of COVID-19 establishing a relationship between infection risk and the mean CO2 level has abruptly led to the measurement of the CO2 concentration in order to limit the spread of this respiratory disease in the indoor environment. Therefore, the extensive application of this measurement outside of traditional air quality assessment requires an in-depth analysis of the suitability of these sensors for such modern applications. This paper discusses the performance of an array of commercial wall-mounted CO2 sensors, focusing on their application to obtain occupancy patterns and air renovation rates. This study is supported by several long-term test campaigns conducted in an in-use office building located in south-eastern Spain. The results show a spread of 19\u2013101 ppm, with a drift of 28 ppm over 5 years, an offset of 2\u2013301 ppm and fluctuations up to 80 ppm in instantaneous measurements not related to concentration changes. It is proposed that values averaged over 30 min, using a suitable reference value, be used to avoid erroneous results when calibration is not feasible.<\/jats:p>","DOI":"10.3390\/s22239403","type":"journal-article","created":{"date-parts":[[2022,12,2]],"date-time":"2022-12-02T03:28:04Z","timestamp":1669951684000},"page":"9403","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Long-Term Assessment of a Set of CO2 Concentration Sensors in an In-Use Office Building"],"prefix":"10.3390","volume":"22","author":[{"given":"Carmen Serrano","family":"Lapuente","sequence":"first","affiliation":[{"name":"Energy Efficiency in Buildings R&D Unit, CIEMAT, Avenida Complutense n\u00b040, E-28040 Madrid, Spain"},{"name":"Plataforma Solar de Almer\u00eda, CIEMAT, Carretera de Sen\u00e9s s\/n, E-04200 Almer\u00eda, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9113-7042","authenticated-orcid":false,"given":"H\u00e9ctor","family":"Herrada","sequence":"additional","affiliation":[{"name":"Energy Efficiency in Buildings R&D Unit, CIEMAT, Avenida Complutense n\u00b040, E-28040 Madrid, Spain"},{"name":"Plataforma Solar de Almer\u00eda, CIEMAT, Carretera de Sen\u00e9s s\/n, E-04200 Almer\u00eda, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5441-5346","authenticated-orcid":false,"given":"Mar\u00eda Jos\u00e9","family":"Jim\u00e9nez","sequence":"additional","affiliation":[{"name":"Energy Efficiency in Buildings R&D Unit, CIEMAT, Avenida Complutense n\u00b040, E-28040 Madrid, Spain"},{"name":"Plataforma Solar de Almer\u00eda, CIEMAT, Carretera de Sen\u00e9s s\/n, E-04200 Almer\u00eda, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0704-2989","authenticated-orcid":false,"given":"Mar\u00eda Nuria","family":"S\u00e1nchez","sequence":"additional","affiliation":[{"name":"Energy Efficiency in Buildings R&D Unit, CIEMAT, Avenida Complutense n\u00b040, E-28040 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,12,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"111092","DOI":"10.1016\/j.envres.2021.111092","article-title":"Assessment of CO2 and aerosol (PM2.5, PM10, UFP) concentrations during the reopening of schools in the COVID-19 pandemic: The case of a metropolitan area in Central-Southern Spain","volume":"197","author":"Villanueva","year":"2021","journal-title":"Environ. 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