[Greenbuilding] ENERGY STAR Clothes Dryers Program Launch

[nick pine]

Reuben Deumling <9watts at gmail.com> writes:

> The fact is that in the 1930s and 40s many of our (US) household 
> appliances were very efficient: water heaters, refrigerators, kitchen 
> stoves, toilets, etc.

A lot of appliances are more efficient today. I lived with an old sidearm 
water heater with NO insulation.

Benjamin Pratt <benjamin.g.pratt at gmail.com> writes:

>The easiest way to make a dryer more efficient would be to increase the 
>amount of air passing through the clothes, and decrease the amount of heat.

But it still takes about 1000 Btu to evaporate each pound of water. We could 
capture and store the sensible heat and use it to warm air for the next 
dryer cycle, but how can we capture the significant additional latent heat 
without a heat pump?

"John Straube" <jfstraube at gmail.com> writes:

> Heat pump condensing clothes driers have ratings of around 250 kWh per 
> year vs 900 for straight electric. These use almost 1/4 as much energy.

Is there a way to make this close to zero?

> I live in a climate that gets below 30F for months. And I have a very 
> energy efficient house with triple glazed fiberglass windows.  Drying 
> clothes on a rack is possible, but results in condensation streaming from 
> the windows.

Slow drying in an insulated airtight closet with a small heat source and a 
dehumidistat and a condensing heat exchanger with closet water vapor on one 
side and room air on the other would avoid condensation on windows, with 
welcome heat of condensation in wintertime, but that still requires 1000 Btu 
per pound of water. How can we make that closer to zero? Multiple-effect 
dehumidification?

Nick