Comparison of the environmental assessment of an identical office building with national methods

Abstract

The IEA EBC Annex 72 focuses on the assessment of the primary energy demand, greenhouse gas emissions and environmental impacts of buildings during production, construction, use (including repair and replacement) and end of life (dismantling), i.e. during the entire life cycle of buildings. In one of its activities, reference buildings (size, materialisation, operational energy demand, etc.) were defined on which the existing national assessment methods are applied using national (if available) databases and (national/regional) approaches. The “be2226” office building in Lustenau, Austria was selected as one of the reference buildings. TU Graz established a BIM model and quantified the amount of building elements as well as construction materials required and the operational energy demand. The building assessment was carried out using the same material and energy demand but applying the LCA approach used in the different countries represented by the participating Annex experts. The results of these assessments are compared in view of identifying major discrepancies. Preliminary findings show that the greenhouse gas emissions per kg of building material differ up to a factor of two and more. Major differences in the building assessments are observed in the transports to the construction site (imports) and the construction activities as well as in the greenhouse gas emissions of the operational energy demand (electricity). The experts document their practical difficulties and how they overcame them. The results of this activity are used to better target harmonisation efforts.

Factors influencing the life-cycle GHG emissions of Brazilian office buildings

“…The obtained range of GHG emissions for Brazilian office buildings is in line with values found in the literature for office buildings, generally ranging from just above 20 to over 100 kg CO 2 -eq/m 2 /year (Airaksinen & Matilainen 2011;Asdrubali et al 2013;Frischknecht et al 2019;Junnila et al 2006;Kofoworola & Gheewala 2008;Kumanayake et al 2018;Lessard et al 2018;Suzuki & Oka 1998;Wallhagen et al 2011;Ylmén et al 2019). As expected, operational energy use was the single most important module for GHG emissions, also associated with the biggest variations.…”

“…The GHG emissions associated with modules A1-A4 (the material production and transport to the construction site) were generally similar to the values found in previous studies (Airaksinen & Matilainen 2011;Asdrubali et al 2013;Frischknecht et al 2019;Junnila et al 2006;Kofoworola & Gheewala 2008;Kumanayake et al 2018;Lessard et al 2018;Ylmén et al 2019). The only significantly higher values were those of more massive structures, due to either height (Yan et al 2010) or national regulations for earthquake-resistant structures (Suzuki & Oka 1998).…”

“…The findings of the sensitivity analysis are generally consistent with the literature. The remarkably high importance of electricity mix for life-cycle GHG emissions was shown by others (Blom et al 2011;Frischknecht et al 2019;Heeren et al 2015;Obrecht et al 2021;Pannier et al 2018;Rossi et al 2012). Heeren et al (2015) reported a relatively small influence of climate on GHG emissions of Swiss buildings, but this discrepancy could be attributed to a smaller range in the analysed climate parameters.…”

“…The method is widely applied to study the environmental performance of buildings, including the assessment of GHG emissions over the life-cycle stages, also known as the carbon footprint (Pandey et al 2011). Numerous studies have been conducted on life-cycle energy use (Cole & Kernan 1996;Dimoudi & Tompa 2008;Junnila et al 2006;Kofoworola & Gheewala 2009;Wang et al 2018;Yohanis & Norton 2002) and GHG emissions (Airaksinen & Matilainen 2011;Asdrubali et al 2013;Chau et al 2012;Dimoudi & Tompa 2008;Eberhardt et al 2019;Frischknecht et al 2019;Junnila et al 2006;Kofoworola & Gheewala 2008;Kumanayake et al 2018;Lessard et al 2018;Suzuki & Oka 1998;Wallhagen et al 2011;Yan et al 2010;Ylmén et al 2019) of office buildings, with some focused on material-related impacts (Chau et al 2012;Dimoudi & Tompa 2008;Eberhardt et al 2019;Yan et al 2010). The available estimates of life-cycle emissions of office buildings vary significantly, as shown in Table S1 in the supplemental data online.…”

Recommendations for Developing a BIM for the Purpose of LCA in Green Building Certifications

“…Although this process is manual and time consuming, it is still the most common way of work as is shown in the aforementioned systematic literature review [29]. This process is possible; however, it leads to wide range of results [61,62].…”