Buildings represent a critical piece of a low-carbon future and their long lifetime necessitates urgent adoption of state-of-the-art performance standards to avoid significant lock-in risk. So far, life-cycle assessment (LCA) studies have assessed buildings (conventional and Zero Emission Building (ZEB)), mobility and energy systems mainly individually. Yet, these elements are closely linked, and to assess the nexus of housing, mobility, and energy associated with human settlements by aiming for Zero Emission Neighborhoods (ZENs) gives a unique chance to contribute to climate change mitigation. ZEBs and ZENs are likely to be critical components in a future climate change mitigation policy.<\/p>\n
This study addresses the challenge of how to use LCA when implementing such a policy, in line also with the introduction of the more stringent Energy Performance of Buildings Directive in 2010 that requires new buildings to be built with nearly ZEB standards by the end of 2020. The specific aims of this report are fourfold. First, to develop and apply an LCA model to support the evaluation of ZEN design concepts with respect to greenhouse gas (GHG) emissions and other potential environmental impacts. Second, to clarify important contributing factors as well as revealing criticalities and sensitivities for GHG emission reductions and environmental performance of such ZEN design concepts. Third, to establish a model basis for other LCA studies on a neighbourhood scale, in terms of a high-quality modelling approach regarding consistency, transparency, and flexibility. Fourth, to apply our model on two cases; a hypothetical case of a neighbourhood consisting of single family house of passive house standard and on Zero Emission Village Bergen (ZVB).<\/p>\n
For the first case, the neighbourhood consists of single-family houses built according to the Norwegian passive house standard. We designed four scenarios where we tested the impact of the house sizes, household size, energy used and produced in the buildings, and mobility patterns. Also, we ran our scenarios with different levels of decarbonization of the electricity mix over a time period of 60 years.<\/p>\n
Our results show the importance of the operational phases of both building and mobility at year 1, and its decline over time induced by the decarbonization of the electricity mix. In year 60, embodied emissions are then responsible for the majority of the emissions when the electricity mix is decarbonized. The most important contributing factors have been identified as the operational phases of the Building and Mobility subsystems when the carbon intensity of the electricity mix is high, and as the embodied emissions in materials when the carbon intensity of the electricity mix becomes low. A reduction of the following factors has been identified as beneficial for the overall GHG emissions of a ZEN: (1) building floor area by house either\/or by inhabitants, (2) passenger cars travel distances by household, which can be achieved by several means; e.g. commuting with public transport and\/or by carpooling initiatives, (3) energy use in the buildings, which is reduced by the use of the passive house standard, and (4) carbon intensity of the electricity mix.<\/p>\n
The second case \u2013 ZVB – consists of residential and non-residential buildings, with a total area of 91 891 m2; 695 dwellings and 1 340 inhabitants. The total emissions associated with the physical elements (buildings, mobility, open spaces, networks and on-site energy) and the life cycle stages (A1-A3, B4 and B6) resulted in a total of 117 kton CO2-eq over the lifetime. This equals 1.5 ton CO2-eq\/capita\/year and 21.2 kg CO2-eq\/m2\/year, referring to heated building floor area and as yearly average emissions over the 60 year analysis period. The emissions are distributed between the elements and life cycle stages. Buildings stand for the majority of the total emissions, accounting for about 52% of the total emissions over the lifetime. The mobility is the second most contributing element, responsible for 40% of the total emissions. The emissions from the networks and open spaces constitute only 2.3% together. A sensitivity analysis showed the emission intensity for electricity and the assumption of allocating emissions from waste incineration to the waste management system rather than to district heat to have a considerable impact on the results. If an EU28+NO electricity production mix is used instead of the Norwegian electricity production mix, total emissions over the 60 years analysis period will increase with 12.5%. This is despite the fact that also negative emissions from the on-site electricity production will be larger, due to the significant increase in emissions from electricity consumed in mobility. If the emissions from waste incineration is not allocated to the district heating production, the total emissions are decreased with 25.3%. Hence, this is a most critical assumption in the LCA model.<\/p>\n
The most important contributing factors have been identified as the operational phases of the Building and Mobility subsystems when the carbon intensity of the electricity mix is high, and as the embodied emissions in materials when the carbon intensity of the electricity mix becomes low. A reduction of the following factors have been identified as beneficial for the overall GHG emissions of a ZEN: (1) building floor area by house or by inhabitants, (2) passenger cars travel distances by household, which can be achieved by several means; e.g. commuting with public transport and\/or by carpooling initiatives, (3) energy use in the buildings, which is reduced by the use of the passive house standard, and (4) carbon intensity of the electricity mix.<\/p>\n
Introducing passive house standards on buildings has the potential to drastically decrease the overall CO2-eq emissions of a ZEB, but also of a ZEN; up to by 191% when assuming an average European electricity mix. Yet, by using a highly decarbonized electricity mix, such as is the case in Norway, the decrease is much lower, around 12%.<\/p>\n
Also, we found the choice of the functional unit to be decisive for the conclusion of the study. When conducting LCAs on a neighbourhood scale, we thus argue for the use of a primary functional unit \u201cper neighbourhood\u201d, and a second \u201cper person\u201d. The use of a \u201cper m2 floor area\u201d unit is misleading as it does not give credits for reducing the total built floor area.<\/p>\n
All these findings demonstrate that the model is capable of long-term analyses of both homogenous and complex neighbourhoods, and provides a detailed understanding of possible future development of the different elements of the neighbourhood and their GHG emissions.<\/p>\n
This report is a part of FME ZEN Work Package 1 Analytic framework for design and planning of zero emission neighbourhoods (ZEN). The goal for WP 1 is to develop definitions, targets and benchmarking for ZEN, based on customized indicators and quantitative and qualitative data. Additionally, an LCA methodology for energy and emissions at neighbourhood scale is developed, as well as a citizen-centred architectural and urban toolbox for design and planning of ZEN.<\/p>\n","protected":false},"excerpt":{"rendered":"
Abstract Buildings represent a critical piece of a low-carbon future and their long lifetime necessitates urgent adoption of state-of-the-art performance standards to avoid significant lock-in risk. So far, life-cycle assessment (LCA) studies have assessed buildings (conventional and Zero Emission Building (ZEB)), mobility and energy systems mainly individually. Yet, these elements are closely linked, and to… Les mer\u00bb<\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[66],"tags":[],"acf":[],"_links":{"self":[{"href":"https:\/\/fmezen.no\/wp-json\/wp\/v2\/posts\/5118"}],"collection":[{"href":"https:\/\/fmezen.no\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/fmezen.no\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/fmezen.no\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/fmezen.no\/wp-json\/wp\/v2\/comments?post=5118"}],"version-history":[{"count":0,"href":"https:\/\/fmezen.no\/wp-json\/wp\/v2\/posts\/5118\/revisions"}],"wp:attachment":[{"href":"https:\/\/fmezen.no\/wp-json\/wp\/v2\/media?parent=5118"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fmezen.no\/wp-json\/wp\/v2\/categories?post=5118"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fmezen.no\/wp-json\/wp\/v2\/tags?post=5118"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}