Dear Jim: I added “smart house” computer controls to make my house more efficient. During even a brief power outage, settings are lost. Are there backup power supplies that don’t waste electricity and are big ones better? – Al S.

Dear Al: Smart house controls run by a personal computer are becoming more commonplace in homes and they can significantly reduce energy usage. By controlling the timing and operation of the heating and cooling systems, ventilation, lights and some appliances, even a house of typical efficiency can operate on less energy overall.

It takes only a very short-duration power outage to cause a personal computer or other electronic control system to lose its settings, possibly requiring reprogramming. If the electric power flutters on and off quickly while the computer hard drive is assessing data, the files can become corrupt or, even worse, the hard drive can be damaged.

You need to use a UPS, or an uninterruptible power supply, at each of your sensitive electronic devices. The power to the computer is not interrupted if the utility power goes off during a storm or accident.

A standard large backup generator with an automatic transfer switch has a delay period until it starts and restores electric power. This delay is too long to keep the computer running without losing data or custom settings.

A UPS system uses a powerful rechargeable battery pack. When a computer is plugged into it, the computer continues to run on the 120-volt house power until there is a power outage or significant voltage drop. Instantaneously, power from the batteries kicks in. The amount of electricity used to keep the batteries charged is very small, even for large, powerful UPS units.

When selecting a UPS, size it properly for efficiency and lower initial cost. The two factors to consider are the maximum power it must provide and for how long. A UPS includes an inverter, which converts battery power to 120-volt house power. If your computer or smart house control draws more power than the inverter can provide, it may overheat and fail and then there is no power.

The maximum power of a UPS is indicated by its VA, or volt-amp, rating. Most electronic equipment lists its VA requirement on the nameplate or packaging. Sum the VAs for all the items to be plugged into the UPS. It might be wise to select one with about 20 percent more VA capacity than currently needed.

The UPS should contain cables and computer software that closes computer files and safely shuts down the computer when the power goes off. This should take less than five minutes, so the UPS does not have to keep the computer running for long. For longer run times, add additional batteries or purchase a larger unit.

The following companies offer UPS systems: APC, 401-789-5735, www.apcc.com; Belkin, 800-223-5546, www.belkin.com; CyberPower Systems, 877-297-6937, www.cyberpowersystems.com; Eaton Powerware, 800-356 5794, www.powerware.com; and Technuity, 800-887-2557, www.energizerups.com.

Dear Jim: I have glass block windows and I want to run a low-voltage electric wire through one to some lights outdoors. Is it possible to drill through the glass blocks without breaking them or reducing efficiency? – Frank C.

Dear Frank: Instead of trying to drill through the glass block itself, drill through the mortar joint between two of the blocks. This is much easier than trying to drill neatly through the glass block itself. If you have to drill through the glass block, use a special drill bit designed for glass. Drill slowly and use a lubricant on the bit. If you break the vacuum seal inside the glass block, it will reduce efficiency.

Send inquiries to James Dulley, Bangor Daily News, 6906 Royalgreen Drive, Cincinnati, OH 45244, or visit www.dulley.com.