Biodiversity burdens in Spanish conventional and low-impact single-family homes.

Biodiversity loss caused by housing is not a well-defined sector of environmental impact. This research quantifies effects on biodiversity of an average Spanish Single-Family House (SFH) with 180 m ² of built surface. The current Spanish SFH stock GWP amounts to 1.16 Gt CO ₂ eq in a 50-year life cycle, 40 % of which is embodied in the building materials and the 60 % are emissions due to the use of the building. This stock also impacts with 10.2 Gt 1,4-DCB the land, water and human health. SFHs also drive 6052 species extinct in a 50 year life cycle, and account for 3.03 M years of life lost due to premature death or lived with a disability. Divided by the 16 M people living in Spanish SFHs, each one lost 0.19 years of their lives (68.1 days) due to their home's impacts on human health. The article compares a reference conventional building against three low-impact cases, to understand how different building techniques and materials influence environmental outcomes that keep biodiversity loss the lowest possible. Scenarios include a standard brick and concrete house as Scenario 0 (SC0, Base), a timber Passivhaus as Scenario 1 (SC1), a straw-bale house with renewable energies as Scenario 2 (SC2), and an earth bioclimatic house as Scenario 3 (SC3). An initial Global Warming Potential (GWP) analysis was performed to relate previous building Life Cycle Assessment (LCA) studies with biodiversity metrics. Three main biodiversity metrics; ecotoxicity (as midpoint indicator), biodiversity loss and damage to human health (both as endpoint indicators) have been considered. Compared to SC0 with 1292 kgCO ₂ -eq·m ^-2 (516 embodied) of GWP, we found that SC1 emitted -47.0 % of that, SC2-41.4 % and SC3-80.9 %. Concerning ecotoxicity, where SC0 has 11,399 kg 1,4 DCB, the results are -27.9 % in SC1, -19.2 % in SC2, and -45.6 % in SC3. Regarding biodiversity loss, where SC0 has 7.54 E ^-06 species.yr·m ^-2 , the impacts are -30.9 % in SC1, -32.6 % in SC2, and -58.6 % in SC3. Human health damage in SC0 being 3.37 E ^-03 DALY, has been reduced in the timber home (SC1) is -44.2 %, of the Straw SFH (SC2) -39.2 %, and of the earth house (SC3) -67.1 %. This article shows that with current existing technological solutions GWP could be reduced in -80.9 %, ecotoxicity in -45.6 %, biodiversity loss in -58.6 % and human health in -67.1 %. Spanish Single-Family Houses built in timber, earth or straw-bale are real alternatives to current cement traditional building.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)