“…coal produces more than 40 percent of the world’s electricity, a foundation of modern life. And that percentage is going up.”
Category Archives: green
My 2 cents on mini-split Air Source Heat Pumps (ASHPs) for heating is:
1) if you calculate the source energy usage, it’s pretty much equiv to using nat gas directly because of the efficiency of power plants being ~33%. So 33% * whatever COP you get from thre ASHP (let’s say 3 as a seasonal winter avg) then you are back to ~1.00. Same as using a 95% efficient gas furnance or boiler in terms of primary energy/source energy.
2) Money wise, you’d also have to do the math with electricity vs gas prices. Because even if the energy use is equivalent, perhaps the price of electricity vs gas/oil is mismatched.
3) And of course, if you source the electricity for the ASHP from wind/etc then that’s better too.
4) But one could also skip the ASHP and just buy New England Wind Fund credits to offset heating energy too.
5) Comfort wise: it’s point-source heat, so if your house doesn’t already have heating zones, then putting one where you spend a lot of time would allow you to drop the temp in the rest of the house.
6) But they are slow to heat up a space, so you can’t really use set-backs you can like with furnaces/boilers that blast! Maybe they wouldn’t work that great for point source heat since it’s not like a hot woodstove.
7) The compressor makes noise outside and you need somewhere to put the thing and shovel snow away from it occasionally
8) Another thing to break
9) Holistically: In addition to Wind Fund offsets, one could also insulate the house more, eat less meat, drive a prius or more efficient car, or move closer to work so you can walk, bike, or drive less. Or fly less.
10) ASHP will also give you AC. So that might be nice.
We built an “almost passive house” a few years back, lived in it for 3 years, but then decided to move. Here are some observations after living in our current “normal 1958 house” for a year.
our almost passive house
+ even temps. all year round. in every room.
+ cheap to run — pretty much zero maintenance, utility bills after solar panel offset were $400 and more like $-1100 after Solar SRECs (versus if you add up our January bills… gas+electric+water+sewer+ice dams it is well over $400 for ONE MONTH!)
+ not even close to an ice-dam (steep roof, smallish overhangs, and very insulated and tight)
+ large dedicated kids room (but since in the attic, our young kids didn’t want to be up there on their own much yet)
+ no need for humidifier in winter or dehumidifier in summer. Always pretty much perfect
+ 105 gallon hot water tank meant less likely to run out of hot water with baths and dishwashing and laundry
our normal 1958 house
+ insanely close to the boys school and friends (so huge savings in time and money/CO2 in driving)
+ closer to grocery shopping
+ closer to Boston
+ just generally closer to lots of things
+ the town we are in has much less sandy soil so easier for gardening
+ if one does feel cold (or hot), the traditional gas-fired furnace is obviously much faster to respond and increase the house temp by a degree or two than the mini-splits in the passive-house. But this only probably happened like once.
+ since we are in a more densely populated place, the house has town water, nat. gas, and sewer. Meaning we could probably actually cook, use water, and have hot water in a power outage.
It I were to do it all again?
Not sure. Maybe by a really inexpensive fixer-upper split level ranch really close to the kid’s school and do a deep-energy retrofit? The problem is: it’s impossible to find such a thing normally. So I dunno. No regrets!
The Problem With Little White Girls (and Boys)
(On voluntourism. From a founder of a summer camp in Dominican Republicfor HIV+ children.)
ME: I am similarly useless. Not to mention the expensive airline tickets (and associated CO2) and (for employed people) the opportunity cost of not doing the work one normally does — the income one could instead donate.
Insulation by definition does not necessarily tighten up a house (think fiberglass batts) but many types of insulation do:
– spray foam
– foam board (as long as it is sealed at seams with the proper tape, and at edges with “good stuff” type spray foam.
So that’s been the story with the insulation we just added to this house:
– walls (there was none) => DENSE PACK CELLULOSE
– garage wall and ceiling separating garage from the house
– attic (loose fill cellulose, lots of spray foam filling up leaks everywhere, and some poly iso foam board on a few knee-wall areas touching living space)
Original blower door was 3000+ CFM50. The one today after the work was 1400 CFM50.
I am not sure I quite believe it, but we’ll see… I believe an inspector will also do a blower-door test.
– windows and doors
– cathedral ceiling (someday…. maybe 4″-6″ of polyiso right on the existing drywall, with new drywall over it?)
LINK: MASS SAVE
Interesting, Washington state has a new-building requirement for SLA — Specific Leakage Area
Is avoiding a 2 degrees C rise “impossible” or is it “difficult but doable” — “…scientists have been dramatically soft-peddling the implications of their research”
Naomi Klein in Russell Brand’s New Statemen issue: http://www.newstatesman.com/2013/10/science-says-revolt