Best Sunroom Glass for San Diego Heat and Sun
Glass is the single biggest factor in whether a San Diego sunroom feels great or turns into a greenhouse. The right glass lets in light while keeping out most of the heat. Here is how to read glass specs and what to ask your contractor for.
Three numbers to know
| Rating | What it measures | What you want in San Diego |
|---|---|---|
| SHGC (solar heat gain coefficient) | How much of the sun's heat gets through, from 0 to 1 | Low, especially on south and west walls |
| U-factor | How fast heat moves through the glass and frame | Low, for a room that stays comfortable year round |
| Visible transmittance (VT) | How much daylight gets through | As high as possible for the SHGC you choose |
For reference, ENERGY STAR's current window criteria call for an SHGC of 0.23 or lower in its two warmest climate zones, along with a U-factor of 0.28 or lower in the South-Central zone and 0.32 or lower in the Southern zone. Those are good benchmarks to ask about for a San Diego sunroom.
Low-E coatings
Low-emissivity coatings are microscopically thin layers on the glass that reflect heat while letting light through. Not all Low-E is the same: some coatings are tuned to keep heat in for cold climates, while others are tuned to block solar heat. For San Diego, ask for a solar control Low-E with a low SHGC.
Dual-pane is the standard
Insulated, dual-pane glass with a Low-E coating is the standard for four-season sunrooms. Single-pane glass or vinyl panels are common on three-season rooms, which are not heated or cooled, but they let much more heat in during summer.
Glass roofs: proceed with care
A glass roof adds light and drama, and also a lot of heat, because the sun shines straight down on it at midday. In San Diego, a glass roof works best on a room that is shaded or faces north or east. On a sunny south or west exposure, a solid or insulated roof with glass walls usually stays far more comfortable. If you want some overhead light, a partial glass section or skylights with a low SHGC are a good compromise.
Safety glass
Building codes require safety glazing, such as tempered or laminated glass, in certain locations like doors and large panels near the floor. Your contractor will show this on the plans. Laminated glass also blocks most of the ultraviolet light that fades furniture and floors.
Glass and California's energy code
A conditioned sunroom, meaning one that is heated or cooled and open to the house, is treated as an addition under California's energy code, which sets limits on the U-factor and SHGC of new windows. Your contractor or designer will document compliance with the permit. This is another reason to choose a contractor who builds sunrooms regularly.
Beyond the glass
- Shading: shades or blinds on west-facing walls make a big difference on summer afternoons.
- Roof: an insulated solid roof is the biggest single upgrade for comfort inland.
- Airflow: operable windows and a ceiling fan help on mild days.
- Heating and cooling: a ductless mini-split is the usual choice for four-season rooms.
See glass sunrooms and four-season sunrooms for design options, or the cost guide for how glass affects price.
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Get a Free EstimateCommon Questions
What SHGC should sunroom glass have in San Diego?
Lower is better on sunny walls. ENERGY STAR's current criteria call for an SHGC of 0.23 or lower in its two warmest climate zones, which is a good benchmark to ask about.
Is a glass roof a good idea in San Diego?
It can be on a shaded or north- or east-facing room. On a sunny south or west exposure, a solid or insulated roof with glass walls usually stays far more comfortable.
Do I need dual-pane glass?
For a heated and cooled four-season sunroom, yes. Dual-pane Low-E glass is standard and helps the room meet California's energy code.
Sources
Andersen: ENERGY STAR Version 7.0 requirements by climate zone. Rules and prices change, so confirm details with your city and contractor.