Recent estimates indicate that approximately 32 percent of the energy used in the U.S. today is for heating and cooling structures in which people live and work. One way to reduce it is to modify the climate which involves planting suitable trees around buildings.

Fall is one of the best times to plant most kinds of trees. Evergreen trees can be used as a windbreak during the cold months and deciduous ones to shade the house during the summer months. After the leaves drop in the fall, the warming rays of the sun will help heat the building during the winter.

If you decide to plant shade trees and don't know which kind to plant, recommendations from the Ohio Agricultural Research and Development Center, Wooster, can be helpful. They stem from 10 years of painstaking evaluation of more than 140 species for urban use.

Norway maples are very tolerant of city conditions and one of the best is the Columnar Norway maple, according to the research report. This tree can be used where there is not much room, grows twice as high as it is broad, grows relatively fast, two feet per year, and is easier to transplant than many of the others.

Bloodgood London planetree (sycamore) is a fast grower. A 10 foot tree after eight years of growth was 23.6 feet tall, 15.3 feet in diameter with a trunk diameter of six inches. It has a mature height of 70 feet.

Red Sunset red maple has a bright orange-red fall color which occurs before killing frost and is generally colorful for one or two weeks. This is considered the best red maple selection for urban and suburban planting.

Select Callery pear has beautiful white flowers in the spring and excellent fall color. After nine seasons it had grown from four to 22 feet high with a 10 feet wide crown. Since it is about twice as high as broad, it's ideal for planting in a confined area.

Dwarf Korean Callery pear is an excellent small tree with an ultimate height of about 20 feet, has excellent white flowers, glossy green foliage and outstanding red fall color.

London planetree is a rapid growing, pyramidal tree widely adapted to downtown. It is very similar to Bloodgood London planetree which is a cultivar of this species.

Snowdrift crabapple is a round- headed, broad, oval tree. The foliage is highly resistant to scab, its straight trunk has limbs to street tree heights, produces abundant white flowers in the spring and its small fruits do not create a maintenance problem.

Marshall Green ash is a very vigorous seedless tree which transplants easily, is expected to reach 55 to 60 feet at maturity and has bright yellow fall color.

Greenspire linden as a young tree has an upright oval form with small, dense, dark green foliage. In city plantings it does very well under difficult conditions. Crotch development is good in this medium textured tree.

Q: I have just planted a B&B (ball and burlap) maple in my front yard. It is about 10 feet tall; should it be staked?

A: Trees that sway back and forth with the wind develop stronger stems and larger measurements than those tied to stakes. However, the soil around newly transplanted trees, whether B&B, container-grown or bare root, is loose and the roots can easily be lifted when the plants sway with the wind. Air pockets can form around the loosened roots allowing them to dry. If roots dry, plants will either die or their growth will be retarded.

Q: I can get a lot of sawdust. Can it be used in the garden to make the soil more acid?

A: Sawdust is an excellent mulch material for the flower or vegetable garden and for strawberry plants, berry bushes and shrubs. There are no mid-May, spread it on the ground around them, keeping about a foot away from the trunk, and they should produce beautiful masses of color during the summer.

Q: Measure worms did a lot of damage to my maple trees last spring. I've been told they will be back again this fall. How can I control them?

A: Measuring worms (fall canker worms) are the larvae of small moths which emerge from the ground in the fall and crawl up tree trunks to lay eggs which hatch in the spring about the time the leaves unfold. They feed on the foliage and can completely defoliate a tree. Spraying with sevin in late April or early May may control them. Directions on the label should be followed closely.