[Greenbuilding] Passive House Overheating
jfstraube1 at bell.blackberry.net
jfstraube1 at bell.blackberry.net
Thu Aug 16 11:17:18 CDT 2012
This whole thread started by mean pointing out that an obsession with hitting an arbitrary heating number can result in overheating and high SHGC are part of the problem.
Without asking people to make many changes in their comfort and their lifestyle superinsulated homes can make very large reductions (eg 3 to 5 times less energy that code built) in their energy use.
Yes one may be able to get to 5.5 times less energy by asking people to accept higher temperatures, operate shades or pay 10K for automatic shades.
My argument is that there are small benefits to some of these approaches and high social or economic costs.
Low SHGC windows, tighter comfort, giving up the arbitrary 15 kwh/m2 heating limit while still accepting the 120 kWh primary energy number hardly seems like that flawed of a way forward.
Sent wirelessly from my BlackBerry device on the Bell network.
Envoyé sans fil par mon terminal mobile BlackBerry sur le réseau de Bell.
-----Original Message-----
From: Corwyn <corwyn at midcoast.com>
Sender: "greenbuilding-bounces at lists.bioenergylists.org"
<greenbuilding-bounces at lists.bioenergylists.org>
Date: Thu, 16 Aug 2012 16:04:23
To: jfstraube at gmail.com<jfstraube at gmail.com>; Greenbuilding<greenbuilding at lists.bioenergylists.org>
Reply-To: Green Building <greenbuilding at lists.bioenergylists.org>
Subject: Re: [Greenbuilding] Passive House Overheating
On 8/16/2012 7:41 AM, John Straube wrote:
> Corwyn, I was joking about the hot humid climate of Maine. Relative to
> most places in the US, it is NOT!
...And even put in an emoticon. Sorry I missed that.
> In many houses, people dont know or
> want to bother opening windows at the right time. Based on the my walks
> through suburbia across the US in the early evening when it is cool
> outside and the AC units on house after house are running, I would
> venture to say this is the vast majority of people.
Possibly. But the same could be said for heating. At which point, we
are both out of a job. :-) If one believes that either energy is going
to get scarce or costly, or that reducing usage is a good in itself,
then accepting what the vast majority of people (in the richest most
wasteful country in the world) do, is not going to solve anything.
If we start at the other end, and assume everyone starts with no status
quo, we can calculate, for example, how much oil everyone gets. This
amounts to 1/2 gallon per person per day (at current production levels).
Given that allotment, do you think the majority would be spending
theirs on air conditioning? Or would they be looking for some other
solution to the heat. I want to be the guy with that solution already
in hand. While 'bother', might be hard to overcome, 'know' is well
within my capability. I am teaching 'energy efficiency by knowledge'
every time I discuss the subject. Someone with more influence could do
much more.
> To me there is not much doubt that you can tweak a design to solve one
> person/family's personal preference and tolerance for high temperature.
> But if we are to make a real differences to millions of new and retrofit
> homes, it seems the safer bet is to make designs that require less
> effort to operate, assume normal comfort tolerances, and assume people
> are not always home and willing to operate components. Yes, this is not
> the least resource solution imaginable, but it is more likely to be a
> real step towards a massive shift rather than a few really low energy
> houses.
If people are unwilling to operate components, we should simply automate
them. However, IMHO operating a few windows is no more effort than
operating a few air conditioners. Nor do you need to be home at unusual
times to do so.
But, if we reach a point where we have exhausted all design options
other than low SHGC glass, is it really the case that that is the lowest
energy solution for Chris Corson? Even if he uses a AC to achieve
comfort, he is going to need around 1.5 MBTUs of cooling (based on the
difference in cooling degree-days vs heating degree-days here) while
losing 5 MBTUs of winter heating. So, I wouldn't recommend lower SHGC
glass.
We aren't going to make a real difference to millions of homes by
treating them all the same. That is how they got the way they are in
the first place. Energy efficiency is a *local* issue. This is, I
think, exactly your point about Passivhaus (with which I heartily
agree). We can never hope to find a solution that works for everyone,
everywhere. My hope is that we *might* be able to find a *process*
which is capable of finding a solution for everyone, everywhere.
Thank You Kindly,
Corwyn
Topher Belknap
--
Topher Belknap
Green Fret Consulting
Kermit didn't know the half of it...
http://www.greenfret.com/
topher at greenfret.com
(207) 882-7652
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