Dear Jim: I live in a fairly new house that needs some landscaping. I think the proper placement of trees could shade the house and lower my air-conditioning bills. How do I go about selecting and placing the trees? – Al R.

Dear Al: Proper landscaping, particularly with trees, can have a great impact on your air-conditioning bills and your comfort. Shade from trees also makes it more comfortable on your outdoor deck or patio and provides an attractive, safe environment for birds and other wildlife.

It is very important to shade not only your windows, but also your house walls, particularly if they are brick or other masonry materials. Masonry slowly absorbs the sun’s heat in the afternoon and radiates it indoors all evening. Most ordinary wall insulation is not effective at blocking this radiant heat.

In addition to just providing shade, trees are natural air conditioners. Their leaves give off huge amounts of moisture that evaporate into the surrounding air. This produces a cooling effect similar to our perspiring. It is an equivalent cooling output to running a large window air conditioner.

As a long-term effect, trees reverse climate change and global warming. One of the primary causes of global warming is increasing levels of carbon dioxide in the air. Trees consume carbon dioxide and convert it to oxygen to counteract our excessive use of fossil fuels.

In most temperate and colder climates, the key to efficient landscaping with trees is to locate them to provide shade, yet allow the sun to shine through during the winter. Leaving an open area to the southwest is ideal. Planting deciduous trees in an arc can actually channel breezes to your house.

In hot, humid climates, the same basic concept applies except that it is best to locate the trees farther from your house. The moisture loss from the leaves can exacerbate already high humidity levels. Also, with high humidity levels, the cooling effect from the leaves is reduced.

In hot, dry climates, it is wise to plant trees closer to the house and select ones that produce a high shading canopy. Trees such as high-crown palms and live oaks allow cooler airflow beneath the shade canopy. Consider the height and shape of the tree as it matures. This allows you to determine how many to plant and how far to locate them from your house. Growth rates and winter hardiness are also important selection criteria.

When making your tree selection, keep in mind that some fast-growing trees are also short-lived and you may have an expensive tree removal job ahead. For the most efficient use of trees, plan on doing quite a bit of pruning.

Write for (instantly download – www.dulley.com) Update Bulletin No. 819 – showing diagrams of landscaping layouts for four climates, selector guide of 100 trees listing heights and shapes, growth rates, hardiness zones and tree care-pruning tips. Include $3 and a business-size SASE to James Dulley, 6906 Royalgreen Drive, Cincinnati, OH 45244.