Life cycle assessment of built-in-storage solar water heaters in Pakistan

Sustainability of building construction and its services is increasingly drawing attention. In this respect CIBSE has issued a number of calls to industry. Solar water heating systems are now economically competitive and are being used throughout the world. Following earlier work of the present authors on the life cycle assessment (LCA) for building components,(1,2) this work presents a monetary, energy usage and environmental impact assessment for solar water heaters. It has been shown herein that for a developing country like Pakistan where large amounts of hot water are required within industry, solar water heating offers favorable payback periods on each of the above three counts. It has been estimated that under the tested conditions, the embodied energy payback period for the plain and finned heater is equivalent to 185 days and 169 days respectively. It has also been found that the amount of carbon released during the construction process of plain and finned water heaters is 27.9 kg and 29.7 kg respectively. Annual carbon saving for the plain and finned water heaters has been calculated to be equivalent to 59.5 kg and 69.6 kg respectively, which in turn gives a carbon payback period of 156 days and 171 days. The monetary payback period for the plain and finned heater has been found to be equivalent to 6.7 years and 6.1 years respectively.