Green retrofitting is a valuable approach for upgrading existing buildings towards sustainable performances. However, the lack of knowledge about the true cost effects and potential savings of green retrofits distracts building proprietors from paying those retrofits. Therefore, the current study reviewed fourteen studies available in the extant literature and identified twenty-eight different green retrofits incorporated into various buildings with their cost effects and saving potentials through a subsequent desktop study. The results indicated that the majority of green retrofits offer savings related to energy consumption, CO2 emissions, cooling load, and operating costs. Moreover, energy-saving lighting modifications are widely done in most buildings, while solar collectors, photovoltaics, and low-emission double glazing are used less often due to the long payback period and increased cost of implementation. Alternatively, the use of retrofits with lower costs and high savings, like BMS, lighting controllers, and boiler efficiency improvements, offsets the above setbacks. Furthermore, the highlighted retrofits include green roofing, bicycle parks, CO2 sensors, and air tightening retrofits, which also save energy. Rainwater harvesting absorbs carbon dioxide and runoff water, where implementing subsystem-level water meters, appliances with low flow rates, and greywater recycling save and recycle the portable water. Accordingly, the study promotes the effective implementation of green retrofits in future buildings.
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