Although older homes often get much of their fresh air supply from air leakage around windows, most new windows are just too tight for that. Trickle Ventilators can be retrofitted to almost any window to permit a controlled air exchange between the living space and the outdoors. The manually controlled vents are installed at the top of the window near the ceiling so incoming air mixes with rising warm air to prevent uncomfortable drafts. The vent is installed over a series of holes drilled through the sash or frame. Costs average between $7 and $8. Order them direct from the manufacturer. Contact: Titon Inc., P.O. Box 6164, South Bend, IN 46660; 219/271-9699. Mortarless Glass Block Last October's review of a mortarless wooden
