Glazing

Put sunscreen or shades on the OUTSIDE of the windows.

This isn't rocket science.

Just to provide a second voice, I agree with lynlynch.

I didn't look up Rwanda on a map, but my guess is that you are closer to the tropics and don't have much of an issue with winter heating--if you do, you might need to consider better insulated windows.

But, assuming the tropics, you don't want better insulated windows--the glass will still let the sun's radiation in, but an insulated window will make it harder for heat to get out. You want to limit the sun's radiation coming in, so shading / sunscreen on the windows is a very good solution. Depending on other weather conditions (high winds, high humidity), you will have to decide what is durable for your situation.

You could also look for a (more modern) window with reflective layers on the outside, but those tend to be expensive--if the windows already exist, find a shade / sunscreen solution. If you have some areas where you want to maintain a view (and your sunscreen is opaque), consider reflective layers on some windows in strategic (i.e., picturesque) locations.

@ rhkramer

Wrong - very wrong! Before giving advice on windows you should study up on the topic.

From your post you are not even a little bit aware of what is available today.

How about enlightening me on what part of what I said is wrong?

Without a reflective coating on the windows, the sun's energy will continue to enter the living space, right?

If the sun's energy continues to enter the living space, it will be converted to heat, and an insulated window will keep the heat in, right?

A shade or solar screen will keep the sun's energy out, right?

A reflective coating will also keep the sun's energy out, right?

So, the thing that I suspect you think I'm wrong on is whether a shade / solar screen on the outside of the building is less expensive than new windows with a reflective coating?

I guess that depends on prices and options available to the OP. For me, in my situation, a shade / solar screen would be much less expensive than new windows.

Depends on what you are doing - the starting point. You nicely turned to cheapest though not a very good solution.

Quote, 'assuming the tropics, you don't want better insulated windows' 100% wrong - double glazed windows are very useful in warm climates. For Energy Star ratings they are even mandatory.

Quote, 'insulated window will make it harder for heat to get out' while true the statement has nothing to do with anything. Insulated windows help keep the heat out and the cool in for which the film only helps keep heat out.

Nothing wrong with shades. I have used reflective films myself - they are OK.

With new windows low E coatings can help in both keeping warm out and cool in.

There are government sites available in the US, Canada & Australia with a wealth of information about fenestration.

Russ

russ123 wrote: Quote, 'assuming the tropics, you don't want better insulated windows' 100% wrong - double glazed windows are very useful in warm climates. For Energy Star ratings they are even mandatory.

russ123: Quote, 'insulated window will make it harder for heat to get out' while true the statement has nothing to do with anything. Insulated windows help keep the heat out and the cool in for which the film only helps keep heat out.

Yes, you're right (or I chose unfortunate wording ;-) --certainly considering that the inside space is air conditioned, you also want to stop heat flow from outside to inside (in addition to the sun's radiation flow).

My point would have been better stated that, given that you already have windows installed, you'll get a significant reduction in heat inside the conditioned area by shading the windows, and I would expect shading to cost less than replacement windows.

Further, the OP didn't state, but maybe the windows are already insulated, in which case there is even less need to consider spending money to replace them.

Of course, depending on how old the windows are, newer windows with higher insulation levels may be available, and an economic analysis may indicate that replacement makes sense, especially with rising energy costs.

Sorry for confusing the issue.

Agreed with your points

Russ

If replacing the entire window assembly:

1) frame with good insulating value - PVC

2) insulated glass - 2 panes with a low E coating on the inside of the outer pane using argon gas for fill

3) depending on the structure height may need to be tempered glass?