Share this page!

Wolfgang Feist Profile picture
Twitter logo
9 Oct, 5 tweets, 2 min read
Actually,we heat our passive house with 1(one) 2.2 kW Minisplit-unit with an investment of less than 2500€ incl. installation.Even if you would use 2 of these (you'd never need more in a #Passivhaus), it's extraordinarely cheap. Total el consumption: 1072(heating)+56kWh(cooling)
There is NO problem if all buildings would use el for such heatpumps (if built to PH standard): max. electric power 525 W (!); no problem for the grid and no problem for a fully renewabale energy generation in this grid. (Your cooking plate has 2000W. )
Uninsulated homes: 4 to 8 times that max. load. Some transmission lines would melt (literally). No place for so many wind-generators; whith a lot of excess electricity during summer.
And, by the way: you simply can't compensate for this by higher SPF of the heat-pumps: There are physical limits for that given by Carnot. The better insulation of the buildings and the MVHR are prerequisites.
Some might think to see a contradiction here with a following tweet (4 times the load - transmisson lines melt). Of coure these don't in case of the cooking plates - but never all of those run at the same time for hours... what will be the case for the heatpumps.

• • •

Missing some Tweet in this thread? You can try to force a refresh
　

Keep Current with Wolfgang Feist

Wolfgang Feist Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

PDF

Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @WolfgangFeist

Wolfgang Feist Profile picture
12 Oct
@fionnstevenson @ElrondBurrell @Conversation Actually, this article talks a lot - but gives no practical recommendation.

#Passivhaus has always recommended 30 m³/Person/h fresh air supply. The air exchange rates given by this will be different in a school/a kindergarden/an office (with e.g. only 1 person sitting there).
@fionnstevenson @ElrondBurrell @Conversation Do the math! In a typical school room that will be 3...6 ach. But, keep in mind, what you can implicitly read in that article: Even the highest vent.-rate will not 100% protect you; yo'll have to wear a mask, too. Because the droplets are in the airstream; and still can hit you
@fionnstevenson @ElrondBurrell @Conversation These are all academic discussions. Now let's be clear, what could be a best possible path to protect us:

1) If indoors and together with other people - wear a mask, and a good one. The mask can't be substituted by ventilation.
Read 17 tweets
Wolfgang Feist Profile picture
28 Jun
As mentioned in the paper: These are outliers, you can easy detect these by your naked eye. There might be outliers also on the "low end"... but, that's irrelevant, because consumption<0 won't happen.
Therefore, outliers on both sides contribute to higher mean value than actually present in this distribution. ( I'll try to quantify later.) Actually, this will not change any of the conclusions of the paper, on the contrary: It will give even more confidence.
Now, we just could say: "We don't care about these outliers, because there's almost no impact on the success for climate change mitigation" - and I agree; and that is also the position of the authors of the paper.
Read 8 tweets
Wolfgang Feist Profile picture
12 Jun
@MarkSiddallRIBA @BarryMcCarron Another independent result confirming [Uhlig 2014]. The measurements have been made in a region with high radon actcivity in the soil. With HRV running, indoor Rn-activity just around the values of external air. Without HRV: see yourself.
@MarkSiddallRIBA @BarryMcCarron What removes Rn also removes other indoor air pollutants: VOC,smells,dust (&the germs connected to dust).The removal rates are similar. Of course,also indoor CO2 is reduced(although that's not a 'pollutant').In one sentence: Indoor air in passive houses has an improved quality.
@MarkSiddallRIBA @BarryMcCarron Important remark: It's not just the HRV. It's all of the following:
(1) really air tight envelope
(to avoid uncontrolled leckage: e.g. Rn coming in)
(2) pure balanced fresh air ventilation (no recirc. air)
(3) quality approved (i.e. PH certified) HRV system
Read 4 tweets
Wolfgang Feist Profile picture
1 Jun
@buildingphysics @PassiveHouseBB @the_iPHA @phplusmag 1/6 #Ongrid or #offgrid is not an inherent part of the #passivehouse standard. You can do whatever you want. That said: Our *recommendation* is to install renewable generation and to connect to the grid.
@buildingphysics @PassiveHouseBB @the_iPHA @phplusmag 2/6 Why not inherent?Because it's of minor importance.The solution of the climate-crisis is to reduce climate-gas emissions as far as possible (to almost zero in 50yrs).This is best done by improving efficiency (a factor 10 is doable). #Passivehouse concentrates on this potential
@buildingphysics @PassiveHouseBB @the_iPHA @phplusmag 3/6 This would be sufficent to solve the problem,because there are enough renewable resources for supply of the remaining very low demand (1/10). But: To reach the goal even faster, we support introducing renewable energy fast.
Read 9 tweets
Wolfgang Feist Profile picture
13 May
@ClarkAllister @douglasbholt @Dr2NisreenAlwan Yes, indeed. here I have to cite Carl Sagan again: "...in an uneasy truce with the more primitive brains beneath...".

Interesting discussion: Yes, of course, we do have to admit that science is not completely unconnected to us.
@ClarkAllister @douglasbholt @Dr2NisreenAlwan 1) This is an one hand trivial - we use our brains to perform science. And our brain is full of bias.

1a It's always easier to accept this, if you look into the past: The geocentric bias was hard to eovercome e.g.. As was the absolute space bias (--> relativity theory)...
@ClarkAllister @douglasbholt @Dr2NisreenAlwan 2) BUT: The scientific method is specifically designed to make it possible to overcome the bias. That has been working several times. Not that it's easy, we always had unpleasant debates. It always was worth it (that would be another thread).
Read 9 tweets
Wolfgang Feist Profile picture
10 May
Now: The following article from Björn Smedman was already published April 11th - now already almost a month ago. In contrast to the assumptions of Tegnell and Giesecke this article has aged well, what is factually very sad.

openias.org/swedens-covid1…
From this article its the first time I understand there the wrong assumptions from the Swedish CDC came from; I thought, that these had been pure speculation; but, I have to apologize, it's not. It was based on facts - but these there interpreted really wrong.
The basic wrong assumption was, that Wuhan had already reached herd-immunity in January and that the lock-down of Wuhan was just futile; the epidemic would have stoped anyhow there.
Read 14 tweets

Did Thread Reader help you today?

Support us! We are indie developers!

This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Too expensive? Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal Become our Patreon

Thank you for your support!

Follow Us on Twitter!

Like this author's thread?

Get email notifications when new thread is out from this Author!

Check out other threads from this Author!

Read all threads by @WolfgangFeist