Reduce — Balance — Generate

The role of our future housing stock in a low carbon future

The transition to a low carbon economy can be fundamentally supported by the right strategic choices being applied to housing in Wales. These choices must consider the following shifts;

• from gas and other fossil fuels for heating, with a significant proportion to electricity
• from fossil fuel for transport, most likely also to electricity for the majority
• towards greater renewable electrical generation for the foreseeable future (<50 years)
• towards alternative/additional power sources in the "unforeseeable" future (>50 years)
• towards a likely +2.8±1°C warming and a wetter, warmer climate

The combination of these probable shifts is a more variable generation of electricity, combined with at least a six-fold increase in electrical demand overall (this is heating alone, not including transport), compounded by demand peaks and supply peaks fundamentally not aligned. This will be occurring in a climate more inclined to wetter, more severe weather conditions, but with no change on the levels of solar irradiance (warmer does not mean sunnier).

The right strategic choices must also consider known factors about housing in Wales that are unlikely to shift significantly, which include;

• Wales has the oldest housing stock in the Western world, and at rates of renewal and given the levels of economic activity underpinning, this appears likely to remain true
• UK private home owners have a poor general record for maintenance of their properties, and an SME industry that delivers much of this work in a lightly regulated or self-regulated fashion
• Despite increasing energy efficiency of individual devices, the proliferation of the number of devices results in an occupancy energy demand that is unlikely to significantly reduce.

The logical strategic role for housing in Wales' Low Carbon future can therefore be summarised as RBG — Reduce, Balance, Generate.

Reduce

With electrical demand soaring due to transport and heating loads switching to electric, housing must ensure it is placed to reduce the demand for energy from these causes first and foremost. This means homes built in the right place to minimise transport energy demands as well as with excellent fabric performance to reduce their heating demands.

Balance

Housing's long life and predictable use align with their use to help shift the energy demands to better align with the energy generation. This can be achieved through technologies or fabric solutions (such as thermal mass) to shift heating demands to match supply, but additionally to include storage for balancing electrical demands (with batteries having less need to be lightweight or small compared to those in electric vehicles). The long life of our homes also provides a means to balance already present carbon emissions through locking atmospheric carbon into construction materials, as well as through associated landscaping & tree cover that can be included within residential development.

Generate

Lastly, where appropriate ownership or maintenance models can be demonstrated, opportunist generation of energy across our housing stock is capable of making a worthwhile contribution to energy generation for Wales. However, this must be done in the context that the vast majority of these homes will outlive the energy generation system mounted on them (even assuming proper and effective maintenance is undertaken), and that these homes will need to continue to be a desirable and pleasant home after this.

The community scale

In addition to the above, it is important for the strategic role of housing in Wales' Low Carbon future to be implemented beyond the scale of the individual home. Achieving any of the RBG steps is less technically and economically efficient if done on a case-by-case basis: this approach requires sizing elements to accommodate 'worst case' instances that are likely to occur very infrequently, but cannot be ignored. This increases material usage and prices whilst still not providing redundancy to individuals. Hence the individual home approach is both uneconomic and inefficient, whilst if suitable professional ownership or maintenance models are not required, also risks placing the operation and maintenance of an increasing part of our national energy generation in the hands of untrained, unfunded and uninterested homeowners.

Homes must therefore be thought of as communities of 'nodes', where 'worst case' events can be distributed across the locality. This approach must be applied to reduction (where some homes will not be able to reduce as far as others), balancing (where some may help balance others), and generation (where energy generation can help local homes not generating at that time). Whilst taken in the context of UK's legal, energy and property ownership frameworks, this is acknowledged as a challenging model, it does represent the most efficient means of delivering the low carbon outcome.