Tuesday, May 29, 2012

Don't Worry About Swamp Cooler Water Consumption

People sometimes worry about the water consumption of an evaporative cooler.   I found this information in an NREL report:

"on a Btu-of-cooling-per-kWh-of-electricity basis, the best evaporative cooling systems are on the order of five times more efficient than SEER 13 central air conditioning (CAC) systems and demand is less by a factor of four or more. Further, additional water use at the site (home) amounts to only about 3 percent of the water use of an average residential customer."

So don't let water costs drive you away from swamp coolers in Denver.

However, if you are building a new, smallish, superinsulated low energy home, you are better off going with a mini-PTHP for heating and cooling.  A swamp cooler requires more maintenance and seasonal mode changeover, which is awkward due to seasonal overlaps like "Indian Summer".

Thursday, May 17, 2012

Reports From the Field - Part I - Zone Valves in Apartment Buildings


Recently I have been performing energy audits of mid-size multifamily buildings, focusing on control problems, the true "low hanging fruit" of energy efficiency for these apartment buildings.

The most common problem we are seeing is zone valves that fail "open".   Tenants will not report this or complain about too much heat until summer.   In summer, no one is looking for boiler problems, and oftentimes the boiler is off for the summer, problem solved unknowingly.

This is not a trivial problem.   Just one zone valve that is fully open all the time in a building with constant circulation will waste at least $30/month.   We've seen 20 unit buildings using $100-$300 /month too much gas when this condition is present.

Landlords are cheap, but here's a situation where you have to spend a  little to save a lot.  The payback period will usually be under two years.   And don't forget:   Every $1000/yr saved in expenses makes your building worth $14,000 more in today's market.

Your average contractor isn't on the lookout for leaky zone valves.   He just wants heat in the apartments and no complaints.   And I can't tell you the reason, but Xcel Energy's energy auditors aren't trained to find problems like this.   

So that means you have to call me.  (720 435-5909)   Another guy in Denver who is great at this type of detective work is Mark Eatherton at 720 375-3107.

Here are my general recommendations:   

  1. If you think that your zone valves are more than 20 years old, replace them ALL.   Seriously.
  2. If they are more than 12 years old have someone check them out to see if any are leaking through.
  3. If you have the 3-wire style zone valves "White-Rogers" more than 12 years old, replace them ALL with Honeywell or Erie valves.   It's not that they are  unreliable, they are just harder to work with.   The average maintenance technician has no idea how they work, so he can't troubleshoot them, and thus you will have to call a more experienced (read expensive) heating tech.
  4. If you suspect your building is using too much gas or electricity, request a usage report from Xcel.  Contact the Building Solutions Center at  BSC@xcelenergy.com  or call  1-800-481-4700  .   Then email it to me at kevdickson@gmail.com and I will compare it to similar buildings and let you know if I think you have any problems.
  5. Don't stop there.   Have your consultant look for other energy wasting issues - more on them later.