Paul Kenny

Integrating occupant preference and life cycle energy evaluation: a simplified method

Building energy evaluation and assessment methods have evolved over the last decades towards sophisticated tools, which can support designers in minimizing building energy use. However, the majority of building energy performance evaluation methods and tools generally do not include a life cycle perspective, choosing to ignore the use of resources associated with the additional materials and systems employed to reduce the energy use of buildings in operation. Considerations of ‘acceptable’ or ‘expected’ levels of comfort or occupant preferences are also frequently ignored outside the research community. This paper describes a simple methodology which integrates life cycle energy analysis and comfort expectations with building energy evaluation. It discusses the potential contribution of the occupants preferences not only in the energy use of buildings in operation, but also the embodied energy associated with equipment and systems. The method is demonstrated in a case study considering a house in a maritime climate with the options of either mechanical or natural ventilation, and some differences in thermal and ventilation preferences. In the study it is observed that as ‘zero heating’ demand is approached, the embodied energy of materials and systems becomes significant. The differences in occupants expected temperature and ventilation levels can be important issues to consider when selecting heating and ventilation systems for minimum life cycle energy use. Les méthodes dévaluation énergétique des bâtiments ont évolué au cours des dernières décennies vers des outils évolués, qui peuvent aider les concepteurs à réduire au minimum lutilisation dénergie dans les bâtiments. Cependant, la majorité des méthodes et des outils dévaluation de la performance énergétique des bâtiments nintègre généralement pas la perspective du cycle de vie, préférant ignorer lutilisation des ressources associées aux matériaux et aux systèmes complémentaires employés pour réduire lutilisation dénergie dans les bâtiments en service. La prise en compte de niveaux de confort «u2009acceptablesu2009» ou «u2009conformes aux attentesu2009» ou des préférences des occupants est également fréquemment ignorée en dehors de la communauté des chercheurs. Cet article décrit une méthodologie simple qui intègre lanalyse énergétique du cycle de vie et les attentes en matière de confort à lévaluation énergétique des bâtiments. Il discute de la contribution potentielle des préférences des occupants, non seulement sagissant de lutilisation dénergie dans les bâtiments en service, mais également de lénergie grise liée aux matériaux et aux systèmes. Une démonstration de cette méthode est apportée par une étude de cas qui examine une maison sous un climat maritime offrant le choix dune aération mécanique ou naturelle et soumise à un certain nombre de différences concernant les préférences thermiques et daération. Il est observé dans cette étude que, lorsque lexigence dun coût de «u2009chauffage zérou2009» doit être satisfaite, lénergie intrinsèque des matériaux et des systèmes devient importante. Les différences relatives aux attentes des occupants concernant les niveaux de température et daération peuvent être des points importants à prendre en compte lors de la sélection des systèmes de chauffage et daération pour pouvoir obtenir une utilisation minimale dénergie au cours du cycle de vie. Mots clés: confort, énergie grise, analyse énergétique, logement, cycle de vie, maisons basse énergie, comportement des occupants

Zero Energy Houses and Embodied Energy: Regulatory and Design Considerations

Building energy performance regulations and standards around the world are evolving aiming to reduce the energy use in buildings. As we move towards zero energy buildings, the embodied energy of construction materials and energy systems becomes more important, as it represents a high percentage of the overall life cycle energy use of a building. However, this issue is still ignored by many regulations and certification methods, as happens with the European Energy Performance of Buildings Directive (EPBD), which focuses on the energy used in operation. This paper analyses a typical house designed to comply with Irish building regulations, calculating its energy use for heating and how water with the Irish national calculation tool, which uses a methodology in line with the EPBD. A range of measures to reduce the energy performance in use of this typical house are proposed, calculating the reduced energy demand and moving towards a zero energy demand building. A life-cycle approach is added to the analysis, taking into account the differential embodied energy of the implemented measures in relation to the typical house base-case, annualizing the differential embodied energy and re-calculating the overall energy use. The paper discusses how a simplified approach for accounting embodied energy of materials could be useful in a goal to achieve the lowest life-cycle energy use in buildings, and concludes with a note on how accounting for embodied energy is a key element when moving towards zero energy buildings.Copyright