The Zero Carbon Britain (ZCB) report¹ estimates that by 2030 we need to have reduced our energy demand by 50% through energy efficiency measures.

To what extent can energy efficiency in the home reduce our domestic energy demand?

Space heating is by far the biggest use of domestic energy and this is where the best possibilities of energy efficiency occur. Through major retrofitting with insulation to existing buildings, and building all new houses to Transition Sustainable Homes code (see Building and Housing Section), we can save 53% of domestic energy demand. Applying additional energy efficiency measures such as behavioural changes (switching off the lights, TV etc when not in use) and changing to energy efficient lighting we can bring this saving to 58% of current demand².

The above estimates are based on a house heated to 21 degrees in the living room with other rooms correspondingly warm (World Health Organisation standards). For every degree we turn the home heating thermostat down, heat loss decreases by 10% and the savings in heating power will be even higher³.

New Buildings

We can assume that all new housing built from 2009 on will have full insulation and energy efficiency standards. However new buildings carry high embodied energy (in 2006 housing consumed 52% of UK energy demand and contributed 25% of CO₂ emissions⁴. We have calculated that to build 519 standard ⁵ houses over the next 21 years would require 21.8 GWh of energy (i.e. 17% of total domestic energy demand). The energy to build these new houses would usually be included under services and industrial data and therefore won’t be included in our local domestic demand calculations. It is included here to indicate the amount of embodied energy.

District Heating

Table 5 indicates that a high proportion of the local renewable energy is produced as heat or hot water:

While this heat can be converted to produce electricity, this process does lose some energy; it is therefore more efficient to use heat directly whenever possible. Where there are larger amounts of heat or hot water produced this can be used on site or piped to nearby buildings to provide district heating. The Holsworthy Biogas plant discussed under 6a(ii) demonstrates how effective this can be. However this relies on close proximity of power generation plants to buildings needing heat and well-insulated pipes. (This principle could also be applied to heated effluents from industrial units; this latter option has not been further explored in this EDAP, due to the low level of industrial activity in the area)

To what extent can reducing personal transportation reduce our energy demand in T&D?

As discussed in depth in the Transportation section of this EDAP, personal transportation accounts for more than 1/3 of our total energy use, much of this is currently from individual short car journeys. The following table sets out the estimated population increases in T&D and calculates the energy requirements for transportation over the next 21 years as we reduce our overall motorised transport use as fossil fuels become increasingly expensive and less available. Without attempting to suggest here how individual formulas for transportation might change over the next 21 years, it is reasonable to assume that out of necessity there will be a fundamental shift from personal car use to mass transit and that we will walk or cycle for more journeys.

The following energy calculations are presented to provide rough data that we can then compare with the energy values of locally produced renewable forms of transport fuel. It is beyond the scope of this EDAP to suggest the numbers of, or individual access to bicycles or electric cars over the next 20 years. The latter is likely to have a role in individual transport as well as providing some off grid electricity storage.

Estimating reduction in annual energy demand for transportation for Totnes & District as population increases but access to personal motorised transport decreases
Year	Estimated % population increase[i]	Calculated population with estimated % increase	Total Energy demand for Transport in T & D
			BAU* Based on 2008 usage (100%) at 10.83 MWh/y	Est. % reduction in energy for all personal motorised transportation	WTC** Est. demand T&D WITH energy efficiency MWh/y	Average total demand per household MWh/y
2008	Baseline	23,863	258,436	Baseline 0%	258,436	27.26[ii]
2011	3%	24,579	266,191	30%	186,333	19.35
2016	7%	25,533	276,522	50%	138,261	14.14
2021	11%	26,488	286,285	80%	57,373	5.82
2026	15%	27,442	297,197	Remains at 80%	59,439	5.99
2031	19%	28,397	307,540	Remains at 80%	61,508	6.15

Methane and bio-diesel are 2 fuels produced by renewable energy technologies, they can be further converted to produce electricity, but the most efficient use is use these fuels to run motors or in the case of gas, used for heating buildings. As fuels, they are suitable for transport. Excluding bio-diesel produced directly from energy crops (which would compete for other uses of land), table 5 indicates the following potential estimated production of these fuels as follows:

When these figures are compared with the estimated demand for transport as set out in table 6, even when reduced to 80% of present demand, there is a substantial deficit in supply:

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