One-off or over-time retrofit?
explores the dimension of retrofit projects by contrasting the comprehensive one-off retrofit model, with a more gradual ‘over-time’ approach; as adopted by many of the Superhomes projects. The paper highlights how an over-time approach, may be well suited to overcoming the capital cost and disruption of undertaking retrofit measures, by spreading their impact over a longer period. Fawcett also highlights how a gradual approach with distinct stages, may fit better with an occupant’s previous experience of building works and home improvement rather than a one-off whole house low carbon retrofit, where a specialist project manager/coordinator may be required. This being said the study does raise the issue of the need for a comprehensive approach to issues such as airtightness, where the entire building fabric will require treatment in order to reduce air permeability. This has important implications for the installation of mechanical ventilation with heat recovery (MVHR).
Retrofit for the future project
It is interesting to contrast; the top down designed Retrofit for the future project had is performance targets derived arbitrarily from the UK Climate Change Act targets of an 80% CO2 reduction. By contrast the super homes initiative has served as a platform for bottom up learning largely funded by occupants, although many have exploited a range of government grants subsidies and other policy measures. Many of the Superhomes project measures were undertaken gradually over a period of several years or more. By contrast the Retrofit for the future project was largely undertaken all in one go, as in some cases the residents were relocated for some of the most disruptive periods .However other studies have shown that it is more cost-effective to install efficiency measures during construction or refurbishment than doing so haphazardly over the life of the building.
Setting a benchmark for Zero carbon new build
Although a number of studies have considered definitions for zero energy buildings including the ZCH have already undertaken significant research for what is deemed achievable under what they term carbon compliance, see section 2.1. The range of standards for low energy and low carbon housing in the UK are described in, with their relative CO2 performance targets shown in. The zero carbon compliance levels broadly adhere to an EIR rating of A. It is therefore proposed that although not directly transferrable an EER rating of A is used to determine those properties that have been built to approximately the level as outlined in the 2016 zero carbon standard. Given that the 2016 target for allowable solutions has been scrapped/ postponed, it is not proposed that any allowable solutions measures or other offsetting schemes are considered in this analysis.
Figure showing Minimum CO2 performance of major UK low carbon building standard