Sat 4 Sep, 2010 12:44 pm
Great op-ed article re saving water, energy and money for air conditioning. This still is a good idea more than ever. ---BBB
Monday, June 23, 2003 - Albuquerque Journal
Upgrading Swamp Coolers Might Be the Better Way
By Kerney Bolton,
The city (Albuquerque) has a drought plan that would ban the use of certain types of evaporative coolers during extreme conditions, and the mayor has recently announced a new $500 rebate for people who convert from swamp cooler to refrigerated air.
We live in a desert and we're short on water, so should we junk our swamp coolers and lay out the big bucks for refrigerated air conditioning?
Converting to refrigerated air will set you back around $3,000-$5,000 plus about $150-$400 a year to operate. At those prices the mayor probably won't have many takers for his $500 rebate except from people who want refrigerated air badly enough to convert anyway.
How about a plan to save water with evaporative cooling. Sounds nuts? Let's take a look.
The simplest evaporative coolers, often called swamp coolers, have thin pads on all four sides and on-off switches for controls. When equipped with bleeders they waste oceans of water. But, disconnect the bleeder and you save thousands of gallons annually.
The bleeder siphons off water to keep salts from building up and clogging the pads. This is total overkill! Given the city's water quality, manually flushing the cooler two or three times a month is very nearly as effective.
If manual flushing doesn't fly with you, install a dump-pump kit for around $50 that will automatically change the water for you. This will use a little more water but far less than a bleeder. If you use the dumped water for irrigation, it will not be wasted at all!
Another way to rev-up a swamp cooler is to add a thermostat and timer kit. It will cost $100 or so, but the cooler will run fewer hours, at lower speed. Water and energy costs will plummet while comfort and convenience improve. Both upgrade kits are available at local building supply stores.
If you want to go all the way, replace your swamp cooler with a fully-loaded, single-inlet evaporative cooler. These $600- to $1,800-units make a swamp cooler look like a Model T! The pad is from 8 to 18-inches thick and produces much cooler air. Dump pumps are standard, and a microprocessor-based thermostat and timer will control speed, water, run time, and dump functions.
So how much water can the city expect to save if we upgrade our swamp coolers or exchange them for single-inlet units?
The fact is, nobody knows for sure. The city has never actually measured swamp cooler water use. The guesstimate is 3.2 billion gallons annually, but only part of that is used by residential evaporative coolers, the rest goes to cooling towers used on commercial and government buildings.
Using a study by the city of Phoenix, which did measure water use and City Planning Department housing statistics, Albuquerque is probably using around two billion gallons annually. Replacing bleeders with dump pumps could save around 900 million gallons, and adding thermostats and timers on swamp coolers, around 300 million gallons more. Alternatively, exchanging swamp coolers for single-inlet evaporative units could save around 1.4 billion gallons.
Conversion to refrigerated air would save an additional 300 million gallons over single inlet coolers.
For a typical new 2,000-square-foot house, cooled by a single-inlet evaporative cooler, annual water use would be around 5,600 gallons for evaporative cooling, 700 gallons for the dump pump, and 600 gallons at PNM to generate the 800 or so kilowatt-hours needed to run the cooler. At 8.5 cents per kilowatt-hour, the annual energy cost would be about $68.
For the same house, refrigerated air would consume 2,800 gallons of water to generate the 3,800 kilowatt-hours needed to power the system. The annual energy cost would be about $325.
The dark side of conversion to refrigerated air comes from that huge increase in energy consumption. According to PNM and EPA energy statistics, and estimates of city housing, refrigerated air conditioning would consume around 100,000 more tons of coal and 700 million more cubic feet of gas, while adding 250,000 more tons of carbon dioxide, 1,000 more tons of nitrous oxide and 400 more tons of sulfur dioxide to our air annually.
If swamp cooler upgrades and exchanges are relatively cheap and save large amounts of water, and conversion to refrigerated air is expensive and unlikely to happen in large numbers, seems like changes in the way we use swamp coolers could save a lot more water, coal, and gas, and fight pollution to boot!
Here is a program we can all live with.
Establish a city-wide evaporative cooling information program.
Mount a campaign to remove bleeder systems from all existing evaporative coolers.
Offer a rebate for all thermostat-timer upgrades.
Ban the use of bleeders in new construction
Set new-construction standards for evaporative cooler sizing, controls, and flushing systems.
Offer rebates for single-inlet evaporative coolers in new construction.
Water is not the only resource that we are wasting in our desert. Fossil fuels can't be replaced and clean air is being fouled faster than it can be cleansed. We have the opportunity to reduce all three, let's roll!
Kerney Bolton works as a residential designer, is a Harvard-educated engineer and a graduate of the School of Architecture and Planning at the University of New Mexico.