Question

We’re adding a sunroom to our home. Can you suggest strategies for natural heating and cooling?

Asked by Dennis Kitchen, Smyrna, TN

We're adding a 15'x15', four-season sunroom to our home. The room will have twelve-foot ceilings, double-hung windows, and a gable roof, and the flooring will probably be tile over concrete. The room will be exposed to western and some southern sun. We'd like to create a space that is as energy efficient as possible, and that takes advantage of natural heating and cooling flows where practicable. What do you think our top considerations should be?

Answer

Mark Schrieber

Answered by Mark Schrieber

Miami, FL

The Spinnaker Group

August 25, 2009

Your sunroom addition can easily take advantage of passive solar strategies, especially if it is isolated from the main house's heating/cooling system.

  • In the winter, you will be able to provide most of the room's heat through passive heating strategies.
  • The choices you make regarding windows, shading, ventilation, insulation, flooring materials, and lighting will all play into the overall energy efficiency of the space.

Shading

You will want shading devices designed to allow direct sun in the winter yet block the higher sun in the summer.

This can be achieved with large overhangs and/or exterior shading devices. (Louvers or awnings are more effective at blocking heat from the sun than interior blinds or shades.)

I would also recommend planting deciduous trees along the south and west exposures, where they can offer shade in the summer but allow light to pass through and heat the room when the leaves fall in winter.

Windows/Ventilation

Ideally you would have windows on all exterior walls to take advantage of cross-ventilation.

The windows should be Energy Star certified to ensure they will reduce heat gain in summer and insulate during winter.

Also consider a ceiling fan to circulate warm air in the winter and draw hot air up in the summer. An opening vent at the ridge line of the roof will create a "stack effect" to naturally cool the sunroom in the summer.

Flooring

Flooring, although typically an afterthought, can affect the overall heating and cooling loads of a building.

To help warm the space in winter, choose a material that has the ability to absorb heat during the day and release it at night. A dark-colored masonry product will work best and should be at least four inches thick to create the passive heating effects desired.

I would not use carpet; in winter you can always add an area rug for additional comfort.

Other Considerations

You could also include a wood-burning space heater as a design and energy feature. If the sunroom is used sporadically and is not connected to the house heat, this can serve as a good system for temporary heat in the winter.

  • Biomass (firewood), like sunlight, is a renewable energy source.
  • You might also consider a Trombe wall, which is a slightly more advanced passive heating device.

You should have a large amount of natural light in the daytime. For nighttime, I would recommend task-specific lighting, such as reading lamps, and LED lighting for minimal electric consumption.

To lessen your cooling loads in summer, I highly recommend that you install a light-colored and well-insulated roof. A white roof will reflect much of the heat that hits its surface, allowing the interior space to remain cooler.

Tagged In: energy efficient window, passive solar, daylighting, shade trees, energy star

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