I use reflectix. First I tape a more apealing color to the class than aluminum. The top is covered as well with hatch doors that can open and close. This allows circulation and a way to let out humidity. I traced the heat lamp and it fits nicely and no longer dries out the air to much. Ambient temps stay nice as does humidity. Reflectix reflects 97% of radiant energy! http://www.homedepot.com/webapp/wcs/...cStoreNum=8125