Straight Talk Articles

What You Do Outside Affects Energy Use Inside
March, 2020

Dear Pat and Brad:  A friend told us that if our landscaping is done right it can help lower our home’s monthly utility bill. What choices can we make that will reduce our home energy use? – Jason and Kit

 

Dear Katie: 

Your friend is right. The decisions you make about your landscaping can help your house stay cooler in summer and warmer in winter.

Since summer’s just around the corner, let’s start by looking at how landscaping can help cool your home.

The biggest overheating problem in summer is sunshine hitting your windows, since the sun is a very powerful source of heat.  Trees that block the sun from hitting windows in the summer will improve comfort and reduce air conditioning (AC) bills. If they eventually grow tall enough to shield your roof, that’s all the better.  Of course, if you’ve invested in solar panels, you don’t want them in the shade.

The most important windows to shade are the west-facing windows, followed by the windows that face east.(1)  The sun in the morning and evening hits the house much more directly than the mid-day sun, high in the sky, hitting the south facing glass. You may even have an eave on the south side that shades your windows pretty well at mid-day.

If you live in a colder climate, planting deciduous trees that lose their leaves in fall will shield your windows in summer but let sunlight in during the winter to help warm your home. A simple approach that can deliver some shade the first year is to plant a “living wall” of vines grown on a trellis next to your house.(2)

One cooling strategy is to make sure your AC compressor has some plants near it.  Just make sure the plants aren’t too close.  The compressor should have a five-foot space above it and a two- to three-foot gap all the way around so that it gets enough air movement to do its job.(3)

There are two other factors to consider that are important in some areas of the country:

  1. Water is becoming more precious and more expensive.When you pay your water bill much of that cost is for the energy to pump the water to your home. Or you may have your own well.Either way, reducing water use saves you money and reduces energy use somewhere.

  2. If you live in an area that has had wildfires you should definitely take that into consideration as you play your landscaping.What you plant and where on your property you plant it can either increase or decrease the risk of fire reaching your home.(4)

 

Now let’s talk about how landscaping affects your home’s energy use and comfort in the winter.

 

If you live in a cold climate, a solid wind break can cut harsh winter wind. The best solution for this is a solid row of trees (preferably evergreen).(5) on the wind-ward side of the home, with shrubs underneath the trees to keep the wind from sneaking underneath.(6) If you live in a warm climate, you probably won’t want a wind barrier as wind flow will help cool your home.(7)

If you live in a cool climate that isn’t too humid, planting a row of shrubs a foot from your home can provide a little more efficiency. By stopping air movement, it can form a dead air space around the house that acts as a little more insulation.(8)   While you’re at it, you could add some foundation insulation if you have a home with a basement or built on a slab.  In a humid climate, however, leave several feet of gap between landscaping and the house, because air flow is needed to avoid moisture-related home damage(9).

These ideas are just the basics.  There is a lot more information available, so you can tailor your strategy to your climate and site conditions. See our More Information page for resources that addresses specific climates and site conditions.

Footnotes

​(1) https://www.eia.gov/todayinenergy/detail.php?id=10271

(2) https://www.energy.gov/energysaver/thermostats

(3) https://www.energy.gov/energysaver/thermostats

(4) http://www.siliconvalleypower.com/for-residents/save-energy/energy-saving-tips/12-easy-ways-to-save-energy

(5) http://www.siliconvalleypower.com/for-residents/save-energy/energy-saving-tips/12-easy-ways-to-save-energy

(6) https://www.energy.gov/articles/top-11-things-you-didnt-know-about-saving-energy-home-summer-edition

(7) https://www.energystar.gov/index.cfm?c=recycle.pr_refrigerator_rep

(8) https://www.energy.gov/energysaver/save-electricity-and-fuel/lighting-choices-save-you-money/how-energy-efficient-light

(9) https://www.energy.gov/energysaver/save-electricity-and-fuel/lighting-choices-save-you-money/how-energy-efficient-light​​

A row of low landscaping along the house can create a dead air space that provides an extra layer of insulation. Photo credit: Lynn Gallagher, Flickr.com

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