Energy is the prime source of human activities in all sectors of life. Traditionally fossil fuel has been the prime source of energy. However, there are two major concerns regarding fossil fuels, i.e. their rapid depletion and their contribution towards growing global warming. It is being widely realized that for sustainable development presently used energy mediums such as fossil fuel and nuclear power have to be quickly replaced by renewable energy sources.

The latter are sustainable and have the potential to meet present and future projected global energy demands without inflicting any environmental impacts. Pakistan is amongst the most prominent cotton producing countries in the world. The affluent availability of local cotton has lead to a well-established textile sector in Pakistan. A large proportion of its cotton products go into export.

Being a successful candidate in international textile market Pakistani textile industry is continuously seeking modern and high-tech facilities to improve quality of its products. The biggest challenge Pakistani textile industry is facing today is how to cut down its environmental burdens to cope with the international standards on the issue. Water heating system as required for dying process is one of the major energy consuming areas in fossil fuel-run Pakistani textile industry.

Water heating system therefore has a significant contribution towards total environmental impacts associated with textile sector. This work presents an alternate, sustainable solution for water heating by means of fossil fuel. It has been shown herein that under Pakistan's climate solar energy can contribute significantly towards this duty. In the present work two different designs of built-in storage water heater-plain and newly designed finned type-were constructed to compare their thermal performance. Three months of experimental data were collected for the two heaters.

The solar fractions for this period were found to be 63 and 73%, respectively. The monetary and embodied energy payback periods for the two heaters were, respectively, found to be 6.7 and 6.1 years, and 185 and 169 days.