Friday, September 12, 2014

Dual Hose Portable Heat Pumps Don't Work Well in Practice

For years I've wondered if a dual-hose portable heat pump/air conditioner would work as a poor man's ductless minisplit heat pump. The advantage, as my logic went, was that I didn't have to drill any holes or charge any refrigerant.
I bought a 14kbtu portable heat pump (Edgestar AP14001HS Portable Air Conditioner)
I did some primitive temperature and airflow measurements.
I was impressed by the overall quality and the 11.2 EER, but what I found was very disturbing.
There is so much internal leakage, that the heat pump blows almost twice as much air out of the house that it pulls in. That difference in air volume gets sucked from outside into the house. The net effect of that is to reduce the COP in heating mode from the advertised 3.3 to roughly 1.4.
For heating, that makes it hardly worth the extra money over a resistance heater. I might as well have purchased an electric resistance heater with a COP of 1.0. In the air conditioning mode, this problem makes the unit worthless except for spot cooling. A window unit would work three times better at a lower first cost.
Has anyone seen a dual hose unit that actually works well?

Monday, September 8, 2014

Pretty Good Duplex HERS Scores

We just finished and sold both units of a spec duplex in SW Denver.  The HERS scores were "pretty good" at 59 and 62.

One of the more important components of the HERS score is the infiltration measurement.  Building Joe Lstiburek identifies 3.0 ACH50 as a pretty good goal.  We scored a 3ACH50 without trying very hard.  The main reason for the good score was the "flash and fill" insulation strategy.  About 3 inches of polyurethane spray foam was sprayed on the inside of the sheathing, and the rest of the cavity was filled with cellulose.

Did the HERS score even come up during the sales or marketing process? Not at all.   Was it good experience for our building professionals in anticipation of the IECC 2012 requirement of 3.0 ACH50?  Absolutely.

Heat Pump Dryer Update

Apparently production of the LG heat pump dryer for the US has been stalled.  A call to customer service yielded no knowledge of it.

But now there is a report that Whirlpool will have one available Q4:

Friday, September 5, 2014

LED lighting update 2014

The LED bulb market is still changing quickly, but IKEA has a 600 lumen dimmable bulb for half the price of the 60 watt equivalent Cree:
The Cree bulb is on the shelf at HD for $9.97: http://www.homedepot.com/p/Cre...
The Cree is 84 lumens/watt and the IKEA is only 60 lumens/watt, so the Cree pays for itself in 3yrs, assuming 3 hours usage per day @ $0.13/kwh
My wife also thinks that the Cree can go dimmer.

Tuesday, July 29, 2014

Update: Combination Washer/Dryer from LG

LG still makes the only full-size washer/dryer combo available in the US.  They have discontinued the old one that I discussed previously.  A new model is now available.   I like combos because you never have to move the clothes from the wash to the dryer, and they save space.


Sunday, July 13, 2014

Bad News for Home Depot Devotees in Denver

I had an estimator from Home Depot come to my office to bid a minisplit installation.  It was the same as calling ARS directly.  He said that all their installations, even for a small 9kbtu unit, start at $9,000 and go up from there.

Saturday, June 7, 2014

Is the "Sharing Economy" a Green Strategy for Denver?

When it comes to housing, airbnb is the most important player in the sharing economy.

Airbnb is a very useful tool to help a building owner eke more money out of his investment. More income means his investment is more sustainable.  The visitors and tourists that use his accommodation will spend money in the neighborhood. That makes the local businesses more sustainable.

Having thousands of airbnb hosts makes a growing city more sustainable because it means that fewer new hotels need to be built. New hotels place a large added burden on the utility infrastructure.

Some cities are resisting the new realities of the sharing economy, and are hampering its growth through unnecessary regulation.

For many years, Denver's zoning law has prohibited homeowners from having lease periods of less than 30 days.  This law has been challenged in Park Hill, but the law prevailed.

Today, Denver's neighborhood leaders tend to be the type of people that want to "preserve neighborhood character".   They do not like short term rentals.  City Council President Mary Beth Susman understands the "sharing economy" and has begun the discussion.   Stay tuned.