Neglecting health effects from indoor pollutant emissions and exposure, as currently done in Life Cycle Assessment (LCA), may result in product or process optimizations at the expense of workers’ or consumers’ health. To close this gap, methods for considering indoor exposure to chemicals are needed to complement the methods for outdoor human exposure assessment already in use. This paper summarizes the work of an international expert group on the integration of human indoor and outdoor exposure in LCA, within the UNEP/SETAC Life Cycle Initiative. A new methodological framework is proposed for a general procedure to include human-health effects from indoor exposure in LCA. Exposure models from occupational hygiene and household indoor air quality studies and practices are critically reviewed and recommendations are provided on the appropriateness of various model alternatives in the context of LCA. A single-compartment box model is recommended for use as a default in LCA, enabling one to screen occupational and household exposures consistent with the existing models to assess outdoor emission in a multimedia environment. An initial set of model parameter values was collected. The comparison between indoor and outdoor human exposure per unit of emission shows that for many pollutants, intake per unit of indoor emission may be several orders of magnitude higher than for outdoor emissions. It is concluded that indoor exposure should be routinely addressed within LCA.

The difference between actual and calculated energy is called the 'energy-performance gap'. Possible explanations for this gap are construction mistakes, improper adjusting of equipment, excessive simplification in simulation models and occupant behaviour. Many researchers and governmental institutions think the occupant is the main cause of this gap. However, only limited evidence exists for this. Therefore, an analysis is presented of actual and theoretical energy consumption based on specific household types and building characteristics. Using a large dataset (1.4 million social housing households), the average actual and theoretical energy consumptions (gas and electricity) of different household types and characteristics (income level, type of income, number of occupants and their age) were compared for each energy label. Additionally, the 10% highest and lowest energy-consuming groups were analysed. The use of combinations of occupant characteristics instead of individual occupant characteristics provides new insights into the influence of the occupant on energy demand. For example, in contrast to previous studies, low-income households consume more gas per m 2 (space heating and hot water) than households with a high income for all types of housing. Furthermore, the performance gap is caused not only by the occupant but also by the assumed building characteristics.

Human exposure to indoor pollutant concentrations is receiving increasing interest in Life Cycle Assessment (LCA). We address this issue by incorporating an indoor compartment into the USEtox model, as well as by providing recommended parameter values for households in four different regions of the world differing geographically, economically, and socially. With these parameter values, intake fractions and comparative toxicity potentials for indoor emissions of dwellings for different air tightness levels were calculated. The resulting intake fractions for indoor exposure vary by 2 orders of magnitude, due to the variability of ventilation rate, building occupation, and volume. To compare health impacts as a result of indoor exposure with those from outdoor exposure, the indoor exposure characterization factors determined with the modified USEtox model were applied in a case study on cooking in non-OECD countries. This study demonstrates the appropriateness and significance of integrating indoor environments into LCA, which ensures a more holistic account of all exposure environments and allows for a better accountability of health impacts. The model, intake fractions, and characterization factors are made available for use in standard LCA studies via www.usetox.org and in standard LCA software.

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A higher conversion efficiency of photovoltaic modules does not automatically imply a lower environmental impact, when the life-cycle of modules is taken into account. An environmental comparison is carried out between the production and use phase, except maintenance, of an indium-gallium-phosphide (InGaP) on multicrystalline silicon (mc-Si) tandem module, a thin-film InGaP cell module and a mc-Si module. The evaluation of the InGaP systems was made for a very limited industrial production scale. Assuming a fourfold reuse of the GaAs substrates in the production of the thin-film InGaP (half) modules, the environmental impacts of the tandem module and of the thin-film InGaP module are estimated to be respectively 50 and 80% higher than the environmental impact of the mc-Si module. The energy payback times of the tandem module, the thin-film InGaP module and the mc-Si module are estimated to be respectively 5Á3, 6Á3 and 3Á5 years. There are several ways to improve the life-cycle environmental performance of thin-film InGaP cells, including improved materials efficiency in production and reuse of the GaAs wafer and higher energy efficiency of the metalorganic chemical vapour deposition process.

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Preamble. In this series of two papers, a methodology to calculate damages to human health caused by indoor emissions from building materials is presented and applied. Part 1 presents the theoretical foundation of the indoor emission methodology developed, as well as characterisation factors calculated for 36 organic compounds, radon and gamma radiation. Part 2 calculates damage scores of building materials with the characterisation factors presented in part 1. The relevancy of including indoor air emission in the full damage scores at a material level and a dwelling level is also quantified and discussed. Conclusion.Health effects due to indoor exposure to pollutants emitted from building materials appear to be dominant in the characterisation factors over outdoor exposure to such pollutants. The health effects of emissions of organic compounds and gamma radiation in the crawl space are very small compared to the health effects of emissions into the other compartments. Using the characterisation factors calculated in this study, it is possible to calculate the human health damage due to emissions of substances and radiation emitted to indoor air and compare this damage with damages to human health associated with the rest of the life cycle of the material. This is the subject of part II of this research.

This paper presents an environmental comparison based on life cycle assessment (LCA) of the production under average European circumstances and use in The Netherlands of modules based on two kinds of III-V solar cells in an early development stage: a thin-film gallium arsenide (GaAs) cell and a thin-film gallium-indium phosphide/gallium arsenide (GaInP/GaAs) tandem cell. A more general comparison of these modules with the common multicrystalline silicon (multi-Si) module is also included. The evaluation of the both III-V systems is made for a limited industrial production scale of 0Á1 MW p per year, compared to a scale of about 10 MW p per year for the multi-Si system. The here considered III-V cells allow for reuse of the GaAs wafers that are required for their production.The LCA indicates that the overall environmental impact of the production of the III-V modules is larger than the impact of the common multi-Si module production; per category their scores have the same order of magnitude. For the III-V systems the metal-organic vapour phase epitaxy (MOVPE) process is the main contributor to the primary energy consumption. The energy payback times of the thin-film GaAs and GaInP/GaAs modules are 5Á0 and 4Á6 years, respectively. For the multi-Si module an energy payback time of 4Á2 years is found. The results for the III-V modules have an uncertainty up to approximately 40%. The highly comparable results for the III-V systems and the multi-Si system indicate that from an environmental point of view there is a case for further development of both III-V systems.