[Greenbuilding] Ductless Heat Pumps (was Central vs window AC)

[Paul Eldridge]

We have two Sanyo inverter-drive ductless heat pumps in our home, a 
forty-four year old, 2,500 sq. foot Cape Cod, and they satisfy just 
about all of our space heating needs (we have an oil-fired boiler for 
backup heat, but haven't required its services for the past two 
winters).  Our local climate is notably colder than that of Buffalo, NY 
and between October 1st and May 31st of this year they consumed a 
combined total of 3,830 kWh and, in return, supplied us with an 
estimated 10,032 kWh of space heat, for a seasonal COP of 2.62.

Our cooling requirements are rather modest (e.g., our forecast high for 
today is 13°C), but during the hottest days of the year we'll run our 
lower level unit in "dry" mode to remove excess humidity (the relative 
humidity as I type this is 97%).  It's much quieter than our portable 
dehumidifier, it uses far less energy and we don't need to empty a 
bucket every other day -- for the other ten or so months of the year, we 
leave the heat turned on to help keep mould and mildew at bay.  One 
additional benefit: the electricity that we use is 100 per cent wind and 
low-impact hydro supplied by Bullfrog Power, which makes their 
operation, for all intents and purposes, carbon-neutral.

Our summary data for the 2011/2012 heating season can be found at: 
http://i362.photobucket.com/albums/oo69/HereinHalifax/HP-2011-2012.jpg

Cheers,
Paul