Window thermal treatments
The question of insulation comes up often. For the old schoolhouse summer is not a problem as it requires very little to no cooling. Heat retention during cold months is the aim.
Possible treatments are:
- double-glazing: requires complete replacement of sash because of the additional thickness and weight.
- storm windows: the primary requirement is the retain heat in cold weather, therefore internal rather than external additions would most likely be used. These need to be removable and storable, therefore they need to be robust as well as effective. Low-E glass or optical grade acrylic would be preferred to minimise visual disturbance but very cheap alternatives are possible, perhaps as a temporary trial, and if the frames are well made then could be reused. Help with drafty windows. Generally detract from window aesthetic.
- internal shutters: not all that effective unless they are particularly tight sealing.
- low-E blinds/shades: cellular shades are the most effective and best when tight fitting
- low-E on-glass films: any that are effective for cold climates are expensive but not compared to other treatments. They are minimally invasive aesthetically but do not fix drafty windows. Here is a comparison.