Sunrooms are a popular way to enjoy the summer without having to deal with seasonal annoyances.  They let the sunlight and the view in while keeping out the bad weather, bugs, and humidity… but they don’t always keep out the heat! Is the only answer a sunroom ventilation system, or are there other things you can do?

How do you cool a hot sunroom?

  There are several reasons your sunroom gets hot in the summer, but the big three are:  
  • Insulation
  • Ventilation
  • And, unfortunately, the sunlight itself
  All three of these are best addressed when you first build your sunroom. But if you already have a sunroom that gets too hot in the summer, we have five suggestions for how you can cool things down.

1) Insulation

  Insulation isn’t just for keeping warm.  Insulation keeps heat from getting in as well as getting out. And good insulation can also keep the humidity out also.   Make sure that you use insulation with a good R-value, and don’t forget to insulate the floor, too. It’s also a good idea to get a vapor barrier for the floor.  Cool air sinks and will seep through the floor there’s nothing to stop it, and this can cause condensation that can damage your insulation and flooring.   The cheapest and easiest time to install insulation is when you are first building your sunroom. But if your existing sunroom isn’t well insulated, never fear, you can usually still have it insulated affordably.   This is because there are so many windows to let the sunlight in, so there isn’t as much wall space in your sunroom that would otherwise require insulation. Also, since sunrooms are often smaller rooms, there’s less floor to insulate.

2) Windows

  The most difficult thing about keeping a sunroom cool in the summer is that the whole point is to let the sunlight in, but sunlight creates heat.  This is called solar gain, and, again, the best time to address it is when you are building your sunroom.   When planning the building you can take summer sun angles into account and try to build so that the hottest rays of the sun don’t get directly in.  You can also choose multi-pane insulated glass and/or glass with tints or low-emissivity coatings that let in a little less light…but a lot less heat.   But if you already have a sunroom that gets a lot of solar gain from direct sunlight, what do you do about it in a room that’s made out of glass?

How can I keep my glass room cool?

  There are things you can do even if your existing sunroom just has regular single pane glass and gets a lot of direct summer sunlight. Do your research–some of these options are more affordable than others.   You can replace your windows with multi-pane insulated glass, but this can be expensive because the materials are not cheap; nor is the labor to custom-cut the glass for your sunroom windows.   A more affordable option may be adding a tint or low-E coating to your existing glass. This can do a lot to reduce solar gain while only slightly reducing actual sunlight.  Low-E is usually more effective than tinting for both letting in light and lowering solar gain, but it’s a bit more expensive.

3) Central Air Conditioning

  A great solution is to simply extend your central HVAC system into the sunroom.  This way your sunroom gets the same air conditioning that your home gets.  But there are a couple of things to watch out for.   For one thing, it’s best if you first address adding insulation and coating/tinting the windows, as discussed above. This is because you’re looking at cooling additional square footage, which will cost more on your energy bill. If your sunroom is badly insulated and constantly heating up due to solar gain, those monthly bills could get really expensive.   Next, make sure your central HVAC is rated highly enough to be able to cool the extra space without strain. Otherwise, it could cause house-wide cooling problems in the summer, and even shorten the lifespan of your HVAC.

4) Ductless Mini-Split

  Another very cool solution is what is called a ductless mini-split system.  These are becoming more and more popular and for good reason. They are small and attractive one-room air conditioning units, or you can get a heat pump for the winter months.   A mini-split has its own thermostat and an outdoor compressor/condenser attached to it via piping instead of ductwork.  This makes it easy to install, quiet, highly efficient, and scalable for the exact size of your sunroom. And because it has its own filter and it recirculates the air in your sunroom, it acts like a dedicated sunroom air quality controller!   This will make your sunroom into its own thermal zone that you can keep a little warmer or cooler than the rest of the house, as you prefer. And its high energy efficiency perfectly meets the challenge of cooling a sunroom in the summer while keeping your energy bill down.   For maximal efficiency, you’ll want to address any needs in insulation and solar gain first. Mini-splits are a great solution, but not a cheap one.

5) Free Standing or Window Unit

If you can’t or don’t want to extend your central HVAC or pay for a mini-split, but you still want air conditioning, you have two more options. As with the other two AC solutions, it’s best if you address any solar gain or insulation issues first.   One option is a window unit, but only if your sunroom has a window that can accommodate one.  While window units aren’t as attractive or quiet as a mini-split, they are almost as efficient, and as long as your sunroom isn’t too big, they’ll do the job.   Another option is a free-standing AC unit. Compared to a window unit, free-standing ACs aren’t generally as powerful or efficient, and they do still need to vent outdoors somehow (usually also through a window). But if your sunroom is small and you have a way to let the standing unit vent outdoors, this could work.   For more information on cooling your sunroom just click here or call us at (703) 721-8888. We’re your go-to for HVAC maintenance services and AC installation in Alexandria, VA, as well as the premier air quality control specialist in Alexandria.