Considerations for extending benefits of energy retrofits at the building level to the building stock

Enhanced energy performance at the building level is mandated through regulations and certifications such as LEED, BREEAM, EPBD, Passivehaus, etc. Their impact is limited due to the large amount of existing buildings where they are not applied. Prefabricated building envelope energy retrofit systems offer viable alternatives for large-scale implementation, reducing costs and installation times while upgrading comfort levels. The number of buildings requiring refurbishment obliges using non-conventional methods responding to a variety of climates. This paper analyses, through computer modelling, two prefabricated retrofit systems placed on the external side of the existing building envelope. The first one includes mainly passive façade technologies with some user intervention, representing a conventional approach to renovation. The second system features mainly active technologies for application on roof and façades. It represents a more ambitious method to upgrade buildings with the latest technologies, where higher energy savings are the main objective. Both systems feature options for use in different climates. Results show the passive system accounted for 50% of energy savings, but the mainly active system reached 65% using finer control responses and a variety of combinations. Choosing adequate design directions from early design stages will affect effectiveness of retrofit policies.