Status and penetration of low and zero carbon homes

New build

The introduction of the mandatory SAP assessment and CO2 performance targets in Part L 2002; in the form of the TER (KgCO2/m2), have been the major tools for ensuring the improved energy performance of new buildings. This was complimented by the introduction of the EPC system in 2008; requiring assessment of all buildings for rent, sale or change of tenure to be assessed against a simplified RdSAP methodology. This has meant that approximately half (13,630,487) (DECC, 2015a) of the UK’s domestic buildings are now accounted for in the EPC system.

However the existing SAP regime has drawn attack for it’s over promotion of low carbon energy generation, rather than fabric energy efficiency (McLeod et al., 2012). With its metric, the SAP rating,  as a measure of the cost-effective performance of a building, potentially creating perverse incentives that may lead to additional CO2 emissions (Kelly et al., 2012).

Niche standards such as the Passivhaus standard may have had limited impact in terms of penetration into domestic buildings in the UK, with around 229 built at present.  However it can be argued that many of the innovations, in terms of improved fabric performance, thermal bridge free detailing, airtightness and MVHR systems; have been increasingly been adopted by the wider industry as a means of cost effectively reducing emissions and energy use from buildings. Indeed the development of a maximum energy consumption standard the FEES (kWh/m2/year), is now a requirement of building regulations, and can be seen as having been significantly influenced by the Passivhaus approach (McLeod et al., 2012).

The ZCH have been the key intermediary organisation for the refinement of the UK legislatory approach to the 2016 zero carbon standard. Prior to the announcement of the apparent mothballing of the zero carbon standard, the ZCH had developed approaches for the Carbon Compliance and FEES standards to be between 10-14 kgCO2/m2/year and 46-39 kWh/m2/year respectively. These were now perceived to be cost effective and achievable for all building types (ZCH, 2014).

This broadly translates to an EPC EER rating of A, and for the purposes of this paper, the A rating is used as a proxy for zero carbon new build. It is acknowledged that this does represent a simplification, and ignores the efficiency of the fabric in relation to low carbon microgeneration and the weaknesses of the SAP/EPC methodology in general.

Notwithstanding these shortcomings, Figure 20 demonstrates the increasing number of EER A rated new buildings being built each year, since the launch of the EPC scheme. Rising from 0.16% to 1.12% of the market share from 2008 to 2014, by the second quarter of 2015 the EPC database indicates that 8,216 EER ‘A’ rated new builds have been constructed (DECC, 2015b) (Blanco, 2009).  However this constitutes only 0.07% of the domestic property built during this period.

In consideration of low carbon/energy building standards as drivers for these properties, we can compare this the total number of properties built to the range of new build standards identified in this report. Table 7 indicates roughly 1,229 houses have been built to these standards, thus representing only 15% of this total.

This represents an important and interesting finding, in that 85% of ‘zero carbon’ homes built to date, have been outside the existing national regime of the code for sustainable homes and other voluntary standards. Admittedly this methodology is fairly crude, in the sense that not all buildings built to the standards shown in Figure 10 may have achieved an EER rating of A, and some other CfSH projects may have achieved an ‘A’ rating. However it does highlight that the majority of properties built to very high energy performance standards in the UK, have been done via the individual specification of the housebuilder.

It may be that a significant portion of these projects may have been undertaken via the self-build route, which constitute approximately 10% of the market in the UK (Heffernan et al., 2015). It can be seen how this model overcomes many of the barriers identified to low and zero carbon technologies; where increased capital costs are recovered in reduced energy bills, technologies are specified on the basis of the user’s needs and desires and therefore are less likely to be susceptible to poor user understanding and reticence to innovate, on the part of the contractor/designer. It is also likely that the FIT for solar PV, may have been a significant driver in these statistics. It can be argued that the greater early uptake of very low energy buildings in Germany as shown by Schimschar et al. (2011), may be in part due to the greater prevalence of the self-build model in continental Europe, and their ongoing support for renewable microgeneration (Heffernan et al., 2015).

Indeed an important are for future study, would be to investigate the significance and role of the procurement and delivery modes for new build housing in the UK, and how these models; self-build, vs. speculative development, affect the adoption of low and zero carbon buildings and innovative or niche solutions.


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