Innovative solutions for sustainable space heating: Integrating solar air heaters and low-cost retrofitting windows for hilly region of Kashmir

The main highlights of the manuscript are as follows • Developing low-cost retrofit window solutions to improve the thermal efficiency of existing windows. • Retrofit windows, designed to fit into existing frames, improve insulation and reduce energy loss without requiring costly renovations. • The primary aim of these retrofit windows is to optimize energy efficiency affordably, minimizing heat transfer and preventing air leaks, thereby reducing energy consumption and utility bills. • The Prototype testing on a thermally insulated test room of size 12*8*10 cubic feet room for solar air heaters under various atmospheric conditions gives a temperature increases of up to 10°C within one hour under different climatic conditions. • Retrofitting demonstrated a 45.69% reduction in energy requirements at a very affordable cost. The Kashmir valley experiences a moderate climate, characterized by cool springs and autumns, mild summers, and cold winters, necessitating heating for approximately 5-6 months annually. Due to unreliable power supply, traditional heating methods such as gas heaters, wood fires, or Kangri's are often relied upon, despite their adverse health and environmental impacts due to emissions of toxic gases. Therefore, there is a need of transition towards non-conventional energy sources. Solar air heaters emerge as a viable option, converting solar radiation into thermal heat which is then delivered to living or working spaces. In addition to minimizing energy requirements for space heating, strategies to reduce heat loss can further enhance energy efficiency. Developing low-cost retrofit window solutions to improve the thermal efficiency of existing windows proves instrumental in this regard. Retrofit windows, designed to fit into existing frames, improve insulation and reduce energy loss without requiring costly renovations. The primary aim of these retrofit windows is to optimize energy efficiency affordably, minimizing heat transfer and preventing air leaks, thereby reducing energy consumption and utility bills while enhancing indoor comfort by maintaining stable temperatures. The several tests were conducted on a thermally insulated test room of size 12*8*10 cubic feet room for solar air heaters under various atmospheric conditions gives a temperature increases of up to 10°C within one hour under different parameters. Furthermore, retrofitting demonstrated a 45.69% reduction in energy requirements at a very affordable cost.