by Annum Rafique
There are approximately 27.6 million dwellings in the UK, which includes houses, flats, mansions, bungalows and park homes. Each year less than 160,000 new homes are being built in the UK. The existing homes undergo renovation over time but the speed of improvement is slow.
These dwelling thereafter referred to as households, consume one-third of the total energy produced in the UK. The main uses of energy in the household are for space and water heating. The energy consumption in households contributes more than a quarter to the total UK Greenhouse Gas (GHG) emissions.
Approximately 75% of the houses in Wales are built before the 1980s due to which Wales has a higher proportion of solid-wall homes and properties off the gas grid. Solid-wall homes are more expensive to insulate. Therefore, the Welsh homes would need individual low-carbon heating solutions, which may cost more per household than the larger decarbonisation of the gas grid.
One of the greatest challenges that water sector faces is the cost effectiveness of decarbonising the sector. The reluctance of households and industry to adopt low or zero-carbon technologies (LZC) usually stems from the additional cost associated with introducing these measures.
The carbon dioxide (CO2) emissions from housing have fallen more than one-fifths from the 1990s despite an increase in the number of homes. The likely reason for the reduction in emissions is due to an increase in building efficiency and lower emissions from switching to an alternative heating source. If the UK wants to become a zero net carbon economy by 2030, it needs to reduce the energy consumption in households.
A study is being conducted to estimate the marginal abatement cost curve (MACC) for water-related energy efficiency measures. The MACC approach is a framework used to identify cost effective low-carbon technologies available for domestic use and determine which mitigation methods are the most cost effective in saving energy as well as in reducing the greenhouse gas emissions.
What is Marginal Abatement Cost Curves (MACC)?
Figure 1 MACC analysis
The MACC is a tool that aid in decision making by identifying the projects that are the most cost effective per unit of CO2 equivalents abated. It also identifies which project or intervention offers the greatest abatement potential.
The MACC provides a visual representation of a group of abetment projects listed down from the most cost effective per tonne of CO2 abatement to the least cost effective option. Figure 1 shows how MACC are represented.
On the vertical axis is the cost per tonne of CO2 abated and on the horizontal axis is the potential CO2 saving in tonnes per year. The MACC provides a visual representation of a group of abetment projects listed down from the most cost effective per tonne of CO2 abatement to the least cost effective option.
MACC allows us to asses all the expected potential costs associated with the low carbon technology such as operating, maintenance and other costs through the lifetime of the technology.
MACC of photovoltaics (PV) systems in households
Figure 2 MACC analysis for small houses
The abatement potential of replacing different kind of boilers with photovoltaics (PV) is measured.
The data for the energy use of households was taken for Gwynedd, Wales from the EPC website. The data consisted of 1,399 houses over 10 years from 2008 to 2018. The houses were of various sizes however, they all use used electricity for water and space heating. While developing MACC, variations in house sizes, types and fuel use was considered.
Energy consumption increases with the size of houses. Furthermore, detached and end-terrace houses consume 30% more energy as compared to semi-detached or mid-terrace houses of similar size.
The fixed installation cost of the PV system is £1,500 with variable costs ranging from £5,320 to £8,512, depending on the size of the system.
Figure 2 shows the MACC for small houses of size between 1 to 55m2. By the uptake of PV system for space and water heating, these houses would be reducing their energy costs by up to 50%. Moreover, the installation of PV would result in an overall savings of £800 to £22,000 per tonne of CO2 abatement. Furthermore implementing PV system in 243 houses of smaller size would save up to 370 tonnes of CO2 every year. These houses, on an average, would be reducing their energy costs by more than a half.
Similar MACCs were created for houses of various sizes and implementing PV systems in all 1,399 houses in Gwynedd would save up to 2,759 tonnes of CO2 each year. Furthermore, it would result in households reducing their energy costs by up to 70%.
However, PV systems are not the only LZC available to consumers. A detailed analysis of other LZC would be conducted to provide complete information to the consumers so that they can make an informed decision.