Figure 1: Carbon Emissions forecasted over 5 years.Figure 2 shows operating costs over 5 years for all three solutions (blue, orange and grey) and the currently employed gas storage system (yellow) is also provided below. Solution 3 highlighted in blue, the gas system costs £52,806. Solution 4, the hybrid system will cost £56,746, whilst solution 5, the all-electric system costs £149,666.
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There are five main solutions presented in this case study for optimal DHW requirements in an archetypal care home:
- Electric immersion cylinders
- Heat pumps
- High efficiency gas water heaters
- Hybrid system comprising of 20% heat pump and gas water heaters
- Hybrid system comprising of 40% heat pump and electric immersion cylinders.
Due to the requirements of the care home and assessing all possibilities against the pre-determined criteria, solutions 3,4 and 5 were viewed as being worthy of further analysis.
Step 4 of the value engineering methodology proposed by Rinnai UK, analyses solution against the current installed system of three non-condensing storage water heaters.
Figure 1 showcases the carbon performance of solutions 3, 4 and 5 as well as the currently installed system of three storage heaters. The colours of each system are highlighted at the top of the graph in blue (Solution 3), orange (Solution 4) and grey (Solution 5).
Figure 1: Carbon Emissions forecasted over 5 years.
Figure 2 shows operating costs over 5 years for all three solutions (blue, orange and grey) and the currently employed gas storage system (yellow) is also provided below. Solution 3 highlighted in blue, the gas system costs £52,806. Solution 4, the hybrid system will cost £56,746, whilst solution 5, the all-electric system costs £149,666.
Figure 2: Operating costs forecasted over 5 years.
Of note is the costs of electricity in the UK which are being targeted by the government to fall by 2035 and be an integral part of cleaning the grid – and note that Figure 2 utilizes Govt forecast statistics.
Figure 3, below, is a graph that illustrates the CAPEX costs associated with each solution. Solution 3 (blue), high-efficiency gas water heaters will cost £25,500. Solution 4 (orange), the hybrid system comprising of 20% heat pump and gas water heaters costs £63,913 and finally, solution 5 (grey) the all-electric system comprising of 40% heat pump and electric immersion cylinders will cost £81,600.
Figure 3: Capital Expenditure required for each solution.
Figure 4 is the final graph that gives the 5-year life cycle costs associated with each system. Solution 3, the gas system (blue) will cost £78,306. 30. Solution 4, the hybrid system (orange) will be £120,658.54. And finally, Solution 5 (grey) – the all-electric system will cost £231,266.35.
Figure 4: Lifecycle costs forecasted over 5 years.
Therefore, the decisive question for the site is whether the reduced carbon emissions of Solution 5 is perceived as far more valuable than the lower lifecycle costs of Solution 4.
Due to the customer’s brief of requirements to include: –
- 20% reduction in carbon footprint
- OPEX considerations
- space for only two heat pumps –
The optimal solution for DHW provision is the hybrid system that includes the 20% heat pump and gas water heaters. It delivers reduced carbon emissions and financial expenditure and can operate within a space limited environment.