Thermal performance of a double pane window using glazing available on the Mexican market

A numerical study of a double pane window (DPW) with three types of commercial glass available in Mexican market is presented. The DPW consist of two vertical semitransparent walls separated by an air gap. The effect of varying the gap width (b) between glasses, the room temperature and the incident solar radiation is analyzed. Simulations were conducted for three configurations; case 1: clear glass + air gap + clear glass; case 2: clear glass + air gap + absorbent glass; and case 3: clear glass + air gap + reflective glass. Optical transmittance and specular reflectance of each case were measured. Two climatic conditions were analyzed, warm and cold climate. The results showed that, in order to increase or reduce the indoor heat gains, from b ≥ 0.02 m, the heat fluxes remains almost constant for both climate conditions. For cold climate, the case 1 reached the highest energy savings (∼10.5 and ∼28.5% higher than cases 2 and 3, respectively), however in warm climate it had the worst behavior (∼105 and ∼177% higher than cases 2 and 3, respectively). Finally, considering the case 1 as reference, the case 3 had the best combined energy saving ($17.64 USD-kWh/year) and case 2 presents a combined energy saving of $7.16 USD-kWh/year. Therefore is highly recommended the use of reflective double pane window, like to case 3, in Mexican warm and cold climates.