“…coal produces more than 40 percent of the world’s electricity, a foundation of modern life. And that percentage is going up.”
Category Archives: erik-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
1. Price of grid electricity. In MA, it can be kinda expensive. And let’s assume you are doing GREEN UP or NEW ENGLAND WIND FUND to make you 100% renewables. Let’s guesstimate $0.20. That might be low, but whatever. It will also increase at rate of inflation. say 3%.
2. Price of solar panels installed. I think it might be even cheaper than this now, but let’s say it’s $4000/KW peak (what the panels are rated)
3. Output of said panels in an average year. I believe in New England, assuming maybe 90% sun (maybe w/ microinverters) and roughly S facing, you can assume 1200 KWh/KW peak. So if you install 1KW of panels, you will get 1200 KWh/year.
4. Borrowing money at 5% for 30 years.
5. Panels will pretty much work with no maintenance (maybe a new inverter) for 30 years. They have a warranty nearly that long. And likely for many more. But we can ignore that.
$4000 at 5% fixed 30 years is $258/year
… EXCEL: = 12 * PMT(5/1200,30*12,4000)
And so that is
$258 / 1200 KW = $0.215/KWh for that electricity in year one
Thirdly: what does that mean exactly?
We are basically at “GRID PARITY” pricing with PVs here in New England from day zero and year one, and…
1. Even assuming NO TAX BREAKS, which there actually are.
2. And things will just keep getting better and better as inflation happens. Even assuming you get costs of living increases at your job which help you keep pace with the equally increasing fossil fuel prices, with the solar, you are locked in to 2013 prices for 30 (or more) years!
Forthly: Comments and Conclusion
One complication is that people move every 7 years I think I’ve heard. So the problem there is that the buyer of your solarized home will not understand all of this wonderful stuff, and solar PVs will be even cheaper 7 years from now, so when you sell, you won’t be able to sell the house for much more with the panels. Maybe a tiny bit. Maybe. And you will still have your extra 5% loan for the PVs to pay off.
And buy a Prius when it is time to buy a new car. And eat less meat. These 2 have been shown (calculations again!) to contribute as much to reducing CO2 as solar panels do. And for many situations they also cost less! And they aren’t attached to the house, so they can come with you when you move.
On the other hand, there are many reasons to do things in life besides money. Most of us live in houses, buy cars, and build kitchens… all far fancier than we NEED. So then… so WHAT if you add some fancy solar panels to the house. If you can afford it, then go for it. They are cool. And the kids will learn a lot from it.
Green building people… if you are designing/building or buying a house, I cannot emphasize enough the importance of this book — A Pattern Language (1977, Christopher Alexander et al.). I also recommend it to those thinking deeply about education, Sudbury Valley School/Democratic Free Schools.
I have skimmed and skipped around, and I am sure there is much hooey to ignore (I certainly can’t speak to the CONSTRUCTION section), but there is MUCH to consider deeply and carefully. Fail to consider the points made at your own risk!!! Lots of food for thought. Don’t worry about the perhaps seemingly haphazard organization of the sections. Just enjoy the sections for themselves.
And I am speaking from personal experience. When I ponder what makes one house or apartment I have lived in comfortable, I inevitably find a number of “patterns” which pretty clearly make sense of it. Here I list some of my favorite sections from the BUILDINGS major section, numbered as they are in the 1200 page book:
(76) House For A Small Family
(In this pattern I think he is wrong… the 2-part house is a typical ranch/rambler/split-level. It’s a question of age. When the kids are little, they love having their beds/room very near the parents.)
(109) Long Thin House (Popular in many green architects designs… I actually don’t like this very much!)
(110) Main Entrance, (130) Entrance Room
(111) Half-Hidden Garden (explains the success of some patios I have experienced)
(112) Entrance Transition, (113) Car Connection
(117) Sheltering Roof
(125) Stair Seats
(127) Intimacy Gradient
(128) Indoor Sunlight (duh but still some interesting comments)
(131) The Flow Through Rooms (Which contains one of my personal favorites — loops “Even better, is the case where these is a loop”. This one is almost NEVER followed in many new smaller houses I look at… but it is fundamental to why many older homes are comfortable. And kids love them! And you will too if you live in New England or somewhere cold!)
(132) Short Passages (as opposed to bowling-alley hallways like one house we looked at recently)
(133) Staircase as a Stage (both our current and last house made good use of this pattern)
(137) Children’s Realm
(142) Sequence of Sitting Spaces
(143) Bed Cluster (partly why the boys’ bedroom is so comfortable)
(154) Teenager’s Cottage (the basement!)
(159) Light on two sides of every room (Nice, but also better ignored in some cases I have found)
(167) Six-foot balcony (porch size rule-of-thumb)
(181) The Fire (“There is no substitute for fire.” Don’t let your dream of a superinsulated passive house let you forget this!)
(190) Ceiling Height Variety (In spades with our current house. love it!)
(192) Windows Overlooking Life (“Rooms without a view are prisons for the people who have to stay in them.”) (SVS related as well)
(196) Corner Doors (yes!)
(197) Thick Walls (Your superinsulated home will have that!)
(203) Child Caves
(242) Front Door Bench, (243) Sitting Wall
(Also, an aside. This book is also very interesting to me because of the way it links to different sections within each of the individual writeups. It is hypertext written before it’s time! It would work well as a PDF E-Book with links to the different sections.)
(9) Scattered Work (Discussing the problem of separation of work from homes)
(12) Community of 7000 (That democratic voices are lost when towns/cities get too big)
(14) Identifiable Neighborhood (We live in one now)
(18) Network of Learning (hmmm… sounds like a Sudbury Valley School (SVS) ad)
(26) Life cycle
(31-33) Promenade, Shopping Street, Nightlife, (58) Carnival
(40) Old people everywhere
And more SVS-related themes:
(57) Children in the City
(64) Pools and Streams
(68) Connected Play
(72) Local Sports
(73) Adventure Playground
(80) Self-governing workshops and offices
(84) Teen-age Society
(85) Shopfront Schools
(11) Local Transport Areas (A diatribe on cars), (20) Mini-buses (half taxi, half bus), (22) Nine percent parking
(51) Green Streets (good for driveways)
“When we do complex roofs in high snow load areas like ski resorts we typically have the roof deck act as the air control layer and provide a high level of thermal resistance at the roof deck (either rigid insulation directly above the roof deck or high density spray foam directly under the roof deck – and then we provide an over roof creating a vented space over the top of the entire assembly. In essence we created a vented unvented roof hybrid. An unvented primary roof assembly with a vented over roof.”
from comment#53 here:
Lstiburek’s Rules for Venting Roofs
You need an airtight ceiling, lots of air flow, plenty of soffit vents, and deep insulation at the attic perimeter
Awesome awesome article on insulating roofs.