By James Dulley, Published June 19 2009
Wise landscaping can boost home efficiencyDear Jim: I plan to do some landscaping myself to save money. I want to make it as efficient as possible for energy and water. What do you think about using gravel or ground-cover plants, and where should they go? – Willis N.
Dear Willis: Most people think of landscaping for just its aesthetic value, but proper landscaping can also affect the energy efficiency of your home. Wise landscaping design can also minimize the need for mowing a lawn. You might even be able to get by with a push mower or a battery-operated one and save the expense for fuel and maintenance.
Several decades ago, concern for minimizing water usage for residential lawns was fairly isolated in the drier Southwestern states. Today with so much population growth, even areas in the typically humid Southeast have water shortages. Clean water is rapidly becoming our most valuable resource.
Both ground cover and gravel have their advantages and disadvantages for landscaping a house. The benefits of either depend upon your climate and your specific house and yard. Even in the same neighborhood, what is good for one house may not be efficient for another.
Low-growing ground cover near your house can help to keep it cool during summer. The leaves block the sun’s heat from being absorbed into the ground and they give off moisture. This evaporation of water from the leaves, called transpiration, actually cools the air similarly to when we perspire. Ground cover has a lesser impact on efficiency during winter.
The cooling effect from the ground cover is most effective in drier climates because there is more evaporation. In hot, humid climates, the additional moisture from the plants near the house will further increase the relative humidity level. This is more of a problem if you rely on natural ventilation than when air-conditioning with the windows closed.
Landscaping with gravel eliminates the need for any watering, but it can increase the air temperature around your house, particularly in the evening. The thermal mass of the gravel stores the afternoon sun’s heat. During summer, this is not good, but during winter, it is an advantage.
If you use gravel, locate it in a spot where it is shaded by deciduous trees during the summer. When the leaves drop over winter, the gravel will be exposed to the sun’s rays and become an effective passive solar heater.
A good location for ground cover is between an asphalt or cement driveway or walkway and the sunny side of your house. Not only does the driveway get hot and hold the heat, but it reradiates the heat up to your house. Planting taller ground cover between the driveway and your house walls can block some of this heat.
Consider the characteristics (mature size, water needs, propagation, foliage density, etc.) of the specific ground-cover plants. To save the most water, group the plant types based upon their watering requirements.
Dear Jim: I have two tubular skylights in my house. They bring in a lot of free light, but one of them dripped water on occasion during cold, clear weather. Where is the water coming from, and how can I stop the dripping? – Russ F.
Dear Russ: A tubular skylight should not drip water. Since it is happening during clear weather, it is not from the rain. The only other source of dripping water would be from condensation inside the metal tube.
The tube should be sealed to keep moist air from entering it. Check the seals at the dome top and the diffuser in the ceiling. Wrapping some insulation around the tube can keep it warmer to reduce condensation.
Send inquiries to James Dulley, The Forum of Fargo-Moorhead, 6906 Royalgreen Drive, Cincinnati, OH 45244, or visit www.dulley.com