IMO blinds do little for insulation use. I use heavy drapes for that purpose. I have never liked honey comb blinds they get yucky and are impossible to get clean . IMO if your windows leak heat you need better windows . I have all thermal paned windows in my house we have some pretty cold days but the windows do not leak air so I never even close my drapes usually. Maybe a bit more info as to your situation would help.BTW my windows are huge and also we have patio doors along our notrh wall still not issue .

I saw a display at Home Depot for a custom shade that was constructed like HD Duette. I can't recall more about them.

Hunter Douglas Duettes were recently approved for the federal energy tax credit. You might be able to stomach the cost.

Make sure your window trim is caulked on the inside. We had a blower door test done and all along the top edges of the trim, air was being pulled in. A bigger project would be to remove the trim to see how well the builder insulated around the window frame.

Energy Star rated double pane argon gas windows only have an R value of about 4, old double panes might be R2. Modern walls are around R13 and higher. Here's a chart with R values of specific cellular shades. It suggests that double cell light filtering shades add 3.3 to the R value.

In my older home, after air sealing, there are no obvious drafts or leaks from the window frames but the vast amount of glass is cold (60+ windows plus glass doors). I like the light and views; heavy drapery is not for me, nor do I like the appearance of cellular shades. However, I will be installing some cellulars for pure function of buffering temperatures. For the most part they will be left up, but lowered for hot sun and cold nights. As Patricia stated, they're not really cleanable. This makes me hesitate to spend the HD prices for them.

I wonder how grimy cellular shades would get. You can vacuum them.

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