We, at the Dept. of Architecture, Faculty of the Built Environment, University of Malaya, Kuala Lumpur, Malaysia, have discovered a low cost alternative to the use of expensive low-emissivity glass used in office buildings to prevent heat egress into the office space. We propose a thin film of a sustainable flowing water film on a cheap ordinary glazing to provide the same or better solar-thermal and solar-optical values as compared to expensive solutions. The water film acts as a lens to allow more daylight into the space while cutting down the heat transmission. The results have been published in peer-reviewed international journal. The research has led to a successful Doctoral thesis at the University of Malaya. The flowing water film could come from simple rain water harvesting systems.