Midcoast Green Collaborative Forum

April 10, 2009

Sustainability Post #43 – Maintenance.

Filed under: Conversation, Philosophy — Tags: , , — Topher @ 10:33 am

[From a discussion on making a house maintenance free, and a comment that humans were the weak link in ensuring energy efficiency]

To my mind, the STRONGEST link is the human. Humans are the best multi-purpose machine yet devised on this planet. By orders of magnitude. An empty house, even without any need to accommodate humans and their needs, is doomed to die in short order. A house loved by humans can potentially last as long as that love lasts.

One of the characteristics of humans is that they get better through practice and repetition. Having a house which needs periodic maintenance trains and encourages the humans to look after it. If a house makes no demands on its humans, they will come to ignore it, and it is doomed. Furthermore, the next house those humans occupy is also in for a hard time.

For example, look at the houses around you, some will be wood, and need paint, some will be mostly ‘maintenance-free’ siding plus some painted trim. Count the percentage of wooden houses which need paint, and compare to the percentage of sided houses which need paint. If your experiences matches mine, the latter will be a larger number, and the condition will be worse.


September 9, 2008

Sustainability Post #31 – Building Shape Efficiency.

Filed under: Conversation, Philosophy — Tags: , , — Topher @ 9:57 pm

While looking at a number of local houses, I noticed the degree to which they suffer from inefficient shapes.  Lots of corners, lots of wall surface area, not much enclosed volume.  Thus hard to heat.  I decided that I needed a numerical value for this concept.  Building Shape Efficiency is thus defined as Enclosed area / (Perimeter / 4) ^2.   A good house should have a Building Shape Efficiency of 93% or more.  Some I have done audits on are under 45%.

How does your house shape up?

p.s. I make no claim to being the first to invent this metric.

August 17, 2008

Home Performance Technician Classes

Filed under: Information — Tags: , — Topher @ 11:34 am

Richard Burbank, who came to the last MGC meeting is teaching a number of courses for energy efficiency professionals.  Details available at: http://www.evergreenbuildingscience.com/

July 2, 2008

Sustainabilty Post #23 — How Much Insulation?

Filed under: Information — Tags: , , — Topher @ 10:50 am

Last week after our  talk on insulation, I sat down to write a post here about what the optimal amount of insulation in a house should be.  Given the recent prices of heating fuels, I thought the speaker undervalued the benefits of insulation.

After a week, and some forays into the world of economics that I would have been happy to skip, I finally have this web page which tries to tell you how much insulation is most economical.  It takes values for fuel type, and price, insulation type, and price (price is divided into fixed costs and variable costs based on thickness of application), mortgage interest (or opportunity cost if no mortgage), and several other things, and computes the optimal amount of insulation, free of any building constraints.

So, how is this useful, you ask, given that there are always building constraints?  Well here are some examples:

1) Your attic,  it is the one place in many house which is free from building constraints.  You can put as much insulation up there as you want.  So, how much is that?  Say, your attic is 26′ by 40′ (1040 square feet), you live in midcoast Maine with around 7500 heating degree days, burn #2 fuel oil at $4.40 / gallon, have a high efficiency boiler at 87%, you think that oil price increases will continue on the current line from 1946 – May 2008 of 2.81% per year,  you are on a fixed income, you can get a 30 year home equity loan for 6.00% to do home improvements, plan to put fiberglass batts perpendicular to the rafters (and existing insulation), which should improve the whole wall factor to 90%, the current insulation is R-20, and the contractor say it will cost $900 (total) for labor, and 10 cents (per square foot) for each inch of thickness.  How much insulation should you add?   19 more inches.  Given that fiberglass only comes in specific thicknesses, this probably means a 6 inch batt and a 12 inch batt.

2) You are building a new house, and are wondering about whether to do 2 x 4 construction, or 2 x 6 on 24″ centers for the walls with dense pack cellulose (both including 1″ foam insulation on the outside).  Using the same economic characteristics as the previous example, and 2000 square feet of wall surface, The whole wall calculator (follow the link on that factor) says that 2 x 4, 16″ on center with 1″ foam outside, has a whole wall factor of 87%, and 2 x 6, 24″ on center with 1″ foam outside has a whole factor of 77%.  And you could discuss that with your builder to see which is cheaper in the long run.  However, there is a problem.  The calculator is telling you that you want 20-22 inches of cellulose in those 2×4 or 2×6 walls.  Oops.  Maybe you should throw out the idea of using old fashioned stick framing altogether.  Perhaps look into double walls or Larsen trusses.

3) You are looking at oil prices and think they are going to track the last five years growth rather than the last 50 years.  That is 36% increases every year.  You are prepared to live under a mound of insulation if you have to, and are planning on buying the newest 97% efficient boiler.    The calculator returns 0, which means you exceeded the limit of 200 inches of insulation.   The solution to your problem is not insulation, but rather ceasing to use oil altogether.

* * *

There are websites (such as this one) which give recommendations for how much insulation you should have.  I have found a couple of problems with them. First, the assume status quo in terms of building construction techniques.  They recommend R-19 for wall because that is what fits in a standard 2×6 wall.  Second, they have embedded assumptions about the price of fuel, and the rate of increase of said, as well mortgage rates and other things.  These assumptions are all hidden and there is no way to change them without going through governmental committees.  Hopefully this site will provide insight into those issues.

It shold be noted that this software is in beta test, and there could be bugs, and it could change without warning.

June 10, 2008

Sustainability Post #17 — First Thoughts on Maine replacement home

Filed under: Conversation — Tags: , — Topher @ 11:39 am

Here is a mock-up I did of my thoughts on a Maine replacement home (to replace energy inefficient single wide mobile homes).  Any thoughts, questions, or criticisms gratefully appreciated.

— Topher

Small single level house with a steep front roof.

copyright 2008 – Green Fret Consulting

May 24, 2008

Sustainability Post #11 — The Right Direction

Filed under: Information — Tags: — Topher @ 6:48 pm

The right direction is True South. That is the way your house should point it’s largest number of windows. Fewer to the West and East, little to the North. This is a basic principle of passive solar design, and it makes a difference even if your house is not full-on passive solar (all houses get a substantial heat boost from the sun).

So how important is it to be exactly South? Not very, a few degrees isn’t noticeable. Too many though and it starts to add up. I took my experimental house (see previous post), and rotated to see how much difference it made (a worst case scenario). Here are the results (fuel costs as a percentage of True South):

180º — 100.00% True South
190º or 170º — 100.87%
200º or 160º — 104.18%
210º or 150º — 109.48%
220º or 140º — 116.09%
230º or 130º — 123.52%
240º or 120º — 132.57%
250º or 110º — 141.81%
260º or 100º — 151.28%
270º or 90º — 162.06% East or West
280º or 80º — 171.26%
290º or 70º — 181.16%
300º or 60º — 190.10%
310º or 50º — 197.40%
320º or 40º — 202.89%
330º or 30º — 206.53%
340º or 20º — 208.73%
350º or 10º — 210.59%
360º or 0º — 211.58% True North

— Topher

Sustainability Post #10 — Replacing Mobile Homes.

Filed under: Conversation — Tags: — Topher @ 12:58 pm

It was brought up yesterday, that a large number of people in Maine who request fuel assistance, live in old mobile homes. And it is likely that they aren’t financially worth fixing. What we really need is a replacement for those houses.

This kept me up last night, thinking of ideas. This morning I ran those ideas through my house energy evaluator, and came up with the following for a very rough plan.

The house would be around 860 square feet, about the same usable space as a single wide mobile home. Two bedrooms, one bath (with no toilet), one half bath (with toilet), open kitchen, dining, living room. Single story, slab on grade (frost protected foundation), vaguely salt box shape.

It would have hot water, and PV panels on the roof that would take care of the energy needs (plus provide income if the FIT bill passes, amounting to around $1200 per year). Without the solar it would require about $1200 per year (current prices)for its energy needs (very roughly).
I note that at $1200 per year, paid to a governmental agency which built it, would not eliminate the need for financial assistance, but would come close to eventually paying for the whole building. No problems with non-payment, foreclosure etc.

It would not be building style dependent, so might be made stick frame in place, straw bale (by DIY builders), pre-built walls (SIPs or the like), possibly even manufactured.

I would love some help in estimating costs, using my preferred building style, if anyone with expertise wants to help.

Of course, this was mostly a proof of concept exercise, and it needs a lot of work before you could build one. (but at least it is out of my head, and maybe I can sleep).

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