Optically Transparent Infrared Mirror

Check out this website, select what wavelength you want to pass and what should be blocked. There are multiple materials on the left and wavelength bandpass graph below.

http://www.globalopticsuk.com/fused-silica.htm

This manufacturer likely can also specify coatings to modify the characteristics to suit your needs.

You may wish to limit the area with windows by building into a hillside, putting solar collectors for hot water, solar electric panels, to increase the 'green' footprint.

add this to the answer for daylighting -

http://www.uc.edu/news/NR.aspx?id=18752

Is that not where a mirror is called a optical color filter?

Filters absorb certain frequencies. With respect to IR this results in elevated temperatures of filters. Mirrors reflect IR energy into the air.

Now a filter that is made of glass with a coating is renamed mirror (or hot mirror?)? IMHO the hot mirror gets hot because it does not reflect the Infrared adequately, but absorbs heat from it. (another sales gimmick?) This principle is as old as the street. Gold has been diffused onto glass for a long time, be it not large scale commercial.

I thought the term 'hot mirror' referred to reflecting heat (IR), and 'cold mirror' was just the case in which IR was allowed to pass.

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That has been my assumption, but now I question it. Do 'hot mirrors' get hot and 'cold mirrors' stay cold?

I have checked these glasses. Behind it is cool but the glass is hot. Especially the multi- layered ones.

Interesting. Thank you.

I think you are describing low-e glass.... the type coated with IR reflective metal oxides.

" most of the common types of glass are good UV absorbers."

This is a bit of a generalisation. Above 300nm yes. Below 350nm perhaps not. Think glasshouses - that rely on transmission of UV and blocking of IR.

I would have thought that blocking UV is important, too.

We all know what UV sunlight does to objects that are not shielded from UV.

Greenhouses do not rely on transmitting ultraviolet. Ultraviolet light reaching the ground typically makes up less than 5% of the total sunlight energy. Greenhouses work just fine transmitting visible light (which makes up most of the energy) and retaining the IR.

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Also, glass typically transmits above, and is opaque below, wavelengths somewhere low in the 300 nm range.

OK You are correct of course that the bulk of the energy will be transmitted into the glasshouse by visible light.

I confused the matter of above and below as I was thinking in terms of the energy of the photon rather than the wavelength.

That is an understandable mix up. I though you might have had something like frequency in mind, while your hand was busy writing in terms of wavelength, especially since the 'above' limit was lower than the 'below' limit you specified.

Absolutely.

Camera and lens manufactures have been doing this for ages with special coatings to the glass.

Of course you can also buy all sort of filters to limit the frequency of transmission. Many of these types of filters are used in astronomy.

May companies, such as This One offer filters or specialty coating that can be applied to your glass to either block IR transmission or a band-pass that is favored toward the IR portion of the spectrum.

I was just looking at a specialty lens from Zeiss with a special IR pass coating to allow IR photography (with the right camera). These types of coatings can just as easily be made for lenses or mirrors.

For the application you are requiring there may be some loss of light in the visible spectrum, but I would consult with an engineer from a company like the one I linked to for specifics.

Great. Thanks A H. did contact them already.