Environmental benchmarks for buildings: needs, challenges and solutions—71st LCA forum, Swiss Federal Institute of Technology, Zürich, 18 June 2019

Abstract

Purpose

The 71st LCA forum was held on 18 June 2019 in Zurich, Switzerland, to discuss the current status and future plans of environmental benchmarking for buildings in view of the 1.5 °C target stipulated in the Paris Agreement. The Paris Agreement requires a significant reduction in greenhouse gas emissions, in fact net zero by 2050. One of the priority areas is the building stock, as it is an important source of greenhouse gas emissions. COP23, the International Energy Agency (IEA) and an increasing number of countries are extending their consideration from aspects such as energy consumption and emissions from building operation to the manufacture of construction materials and building construction. The event offered an excellent platform to exchange ideas and thoughts on existing and planned environmental benchmarking schemes for buildings.

Methods

The one day event dealt at first with life cycle assessment (LCA) approaches applied in European, Asian, Australasian and American countries to assess the environmental performance of buildings. Within a round robin test, organised within the IEA EBC (Energy in Building and Communities) Annex 72 project, 22 organisations from 21 countries assessed the environmental performance of one identical building, the be2226 office building located in Lustenau, Austria. The materials, the building technologies and the energy consumption were kept constant. This allowed to identify the main differences in LCA data used and LCA methodology applied in the national contexts. In the LCA forum, eight organisations presented the current state or future plans of an environmental benchmarking system in their home country. The systems were characterised in terms of scope, in particular (a) which types of buildings are covered; (b) which life cycle stages are included; (c) which building elements and which operational energy uses are considered; and (d) which environmental impacts are addressed. Furthermore, the default reference service life and the main source of LCA data were specified and the current or planned benchmark values for greenhouse gas emissions of residential buildings were reported.

Results and discussion

The round robin test revealed the LCA background data as one major source of difference in assessment results. Methodological and modelling choices were less important except for the Danish assessment, which applies a comparatively long reference study period (80 years for office buildings, 120 years for residential buildings) and considering future changes in the electricity mix towards 100% renewables to describe the operational electricity demand during the lifetime of the building. Most benchmarking systems presented are applied on new and retrofit residential, office and school buildings. Other use types such as shops, restaurants, universities or hospitals are covered only in few or just one country. The greenhouse gas emission benchmark for residential buildings (construction and operation) revealed a significant gap between the current level of the building benchmarks on one hand and the target of net zero CO₂-eq emissions derived from the 1.5 °C scenarios of IPCC on the other. An online inquiry carried out among the audience during the event showed a preference for a per capita overall budget of 500 kg CO₂-eq per year to derive greenhouse gas emission benchmarks for buildings and that life cycle-based benchmarks for buildings should be legally binding.

Conclusions

The 71st LCA forum on environmental benchmarks for buildings showed that the experts present acknowledge the net zero CO₂ emission target derived from the 1.5 °C scenarios. Several countries have expertise and experience in assessing the environmental impacts of buildings. However, the current (mostly voluntary) benchmarking schemes are way too weak to support the building sector in contributing significantly to the required CO₂ emission turn off. The outlook given by several speakers showed that the current benchmarks will likely be tightened and oriented on the planetary boundaries and on the scientifically defined CO₂ emission budgets rather than on the technical or economic feasibility. Finally, the responsibility of governments for defining environmental requirements and targets was stressed. The event, the exchange of ideas and the discussions helped to nurture and hopefully accelerate the developments in the construction sector of the home countries of the experts and government representatives. These developments will contribute to a society whose environmental impacts remain within the carrying capacity of our planet.