Passivhaus philosophy resource? I have a few questions around ideal temperature

[puntloos]

A lot of the "lore" of how to live in a house is based on assumptions that don't work in a new build passivhaus. 

 

For example, most recommendations I see around house temperature seem very tinted by trying to be energy efficient in a non-energy-efficient house. "dropping the thermostat 1C" is well and good if your house wants to go to 15C and you need it to be at least  20, but my house stays at 22 without much help, and for me, dropping the thermostat 1C raises the cost because it turns on my air conditioning!

 

Instead, a recent Harvard Study - Nighttime ambient temperature and sleep in community-dwelling older adults suggests "20-25C" - so call it 22.5C nighttime ambient temperature is optimal. 

 

But then.. 22.5C, well, perhaps also because of temperature assumptions, I'm a little hot in my house if I wear sweaters. Should I take those off instead?

 

Is there any discussion on how a passivhaus, with people in it, should behave? 

 

[JohnMo]

2 minutes ago, puntloos said:

suggests "20-25C" - so call it 22.5C nighttime ambient temperature is optimal. 

Maybe in some other universe, or where ambient is constantly 30 or above, but I wound prefer 16.  Airtight and even with 0 outside the other night, we had the bedroom window open.

[joe90]

No two people are the same re comfort levels, I don’t like being overheated and that would be anything over 20’ in my case. I am sat in the North facing shaded part of my cottage at 18’ with the doors open and feel very comfortable but I know others would not be.

[puntloos]

2 minutes ago, JohnMo said:

Maybe in some other universe, or where ambient is constantly 30 or above, but I wound prefer 16.  Airtight and even with 0 outside the other night, we had the bedroom window open.

I think it certainly goes to show it matters what you're accustomed to. But especially if you are actively (ASHP?) trying to heat or cool a place to match what you're used to, you might need to ask yourself some questions on what you're doing. 

 

To be clear, IMO a house should ideally be good for what you want rather than that you try to adapt to the house, but I've found with passivhaus there's a very new and pretty unknown (to the public) balance to be struck between trying to live low-energy and tolerating some good variation between hot and cold. 

[ProDave]

We are happy with 20C in the living rooms but prefer about 18 in a bedroom, which is why the bedroom window spends a lot of time open.

 

The BIG difference with a passive or passive principle house is the internal temperature never changes quickly.  So forget the old concept of heating on when you are in the house and heating off (and let the house cool down) when you are out at work.  It simply won't cool down any meaningful amount.

[Gone West]

34 minutes ago, puntloos said:

But then.. 22.5C, well, perhaps also because of temperature assumptions, I'm a little hot in my house if I wear sweaters. Should I take those off instead?

We never wear sweaters indoors, we consider them outdoor wear. When we lived in our PH we had the whole house at 23C all the time. We don't find 23C hot for a bedroom. We wear comfortable clothing indoors which for me is a T shirt and sleep with a 4 TOG duvet. We have continued living in the same way in our latest old stone walled bungalow and are reducing the heat loss to reduce the cost.

[puntloos]

3 minutes ago, Gone West said:

We never wear sweaters indoors, we consider them outdoor wear. When we lived in our PH we had the whole house at 23C all the time. We don't find 23C hot for a bedroom. We wear comfortable clothing indoors which for me is a T shirt and sleep with a 4 TOG duvet. We have continued living in the same way in our latest old stone walled bungalow and are reducing the heat loss to reduce the cost.

 

35 minutes ago, joe90 said:

No two people are the same re comfort levels, I don’t like being overheated and that would be anything over 20’ in my case. I am sat in the North facing shaded part of my cottage at 18’ with the doors open and feel very comfortable but I know others would not be.

 

Two "conflicting" points of view, which just goes to show that at the very least there's personal differences. Whether or not they are learned or "genetic" is perhaps a different discussion, I have always assumed (for example) that people from warmer countries would want a place to be warm, but Indian friends of mine want the place freezing, and a polish friend gets cold really quickly

 

In the end, I think the crucial part is that Passivhaus only 'dictates' a house shouldn't be more than 25C which is a reasonable maximum also given the research I quoted earlier. For comfort I seem to be gravitating to 23C but I'll admit the moment I start doing 'manual labour' in the house, eg tidying moving a sofa, whatever, then I overheat quickly if it's already 24.5. 

 

But yes, sweaters are great to wear indoor if you are doing it to keep the cost of limiting the heating cost, but it's silly to try to cool the house to be able to tolerate wearing sweaters. 

[Gone West]

2 hours ago, puntloos said:

For comfort I seem to be gravitating to 23C

It's not a number on a thermometer that matters, it's whatever you find comfortable that's important.

[garrymartin]

6 minutes ago, Gone West said:

It's not a number on a thermometer that matters, it's whatever you find comfortable that's important.

Spot on. And that can change over time too as the occupants age.

 

I've also read somewhere that the air quality and lack of draughts in Passivhaus generally means the temperature can be lower than in a BR-compliant house and still feel the same. 

[SteamyTea]

I think, in the UK, because we have distinct seasons (caused by our latitude) AND variable weather (causes by being an island) we, the British, are very sensitive to our climate.

We also have thermally dreadful housing stock, high incomes and low energy costs (I know there are extremes, but the median figures support this).

Much of the 'energy saving' mentality goes back to the switch from solid fuel, to town gas, then naturally gas, and the energy crisis if the early 1970s (just as we were told gas would be the cheapest ever and electricity too cheap to meter).

So no we sit in over heated houses, ventilated by cold draughts and rattling windows.

I suspect that the reason that many people say they like a colder bedroom, or the window open, has nothing to do with temperature, more to do with humidity control.

 

There was a campaign, in the 1980s to get us to turn the heating down, claims like 1⁰C lower on the thermostat can save you 20% on the bill.

This is a statistical arguement based in heating degree days, and in some, limited cases  may be true.

But for most people it is not true, partly because a leaking house soon cools, partly because our heating systems are crap, and mainly because most people are scientifically illiterate and because of ingrained ignorance and prejudice, cannot set a thermostat to the right place.

 

So what to do?

Find a temperature that suits you, not what your friends suggest.

 

I would happily have a place at 28⁰C at night, that is 12⁰C cooler that where I grew up. And even at 85% humidity, it is still dryer here.

 

[puntloos]

1 hour ago, Gone West said:

It's not a number on a thermometer that matters, it's whatever you find comfortable that's important.

Not to mention, frankly, I find thermometers so misleading! I am still suspicious of their overall accuracy is it really xyz degrees or would a premium thermometer disagree?

But even more importantly, what is "it". In my home, the temperature on our wall touchscreens is, I believe, the average of all measurements in that room, of, well, what.. I suppose these devices are measuring their own temperature, so if they're stapled to a wall, are they measuring wall temperature? Etc. 

 

But yes as you said, if you're OK, you're ok. 

[puntloos]

58 minutes ago, SteamyTea said:

I think, in the UK, because we have distinct seasons (caused by our latitude) AND variable weather (causes by being an island) we, the British, are very sensitive to our climate.

We also have thermally dreadful housing stock, high incomes and low energy costs (I know there are extremes, but the median figures support this).

Much of the 'energy saving' mentality goes back to the switch from solid fuel, to town gas, then naturally gas, and the energy crisis if the early 1970s (just as we were told gas would be the cheapest ever and electricity too cheap to meter).

So no we sit in over heated houses, ventilated by cold draughts and rattling windows.

I suspect that the reason that many people say they like a colder bedroom, or the window open, has nothing to do with temperature, more to do with humidity control.

One problem on that one is that "supposedly" (I saw it somewhere on the internet so it must be true..) passivhauses are a little harder to control for humidity, and I do indeed find that my house humidity seems to sit a little above ideal - 60-65%)

58 minutes ago, SteamyTea said:

There was a campaign, in the 1980s to get us to turn the heating down, claims like 1⁰C lower on the thermostat can save you 20% on the bill.

This is a statistical arguement based in heating degree days, and in some, limited cases  may be true.

But for most people it is not true, partly because a leaking house soon cools, partly because our heating systems are crap, and mainly because most people are scientifically illiterate and because of ingrained ignorance and prejudice, cannot set a thermostat to the right place.

 

So what to do?

Find a temperature that suits you, not what your friends suggest.

 

I would happily have a place at 28⁰C at night, that is 12⁰C cooler that where I grew up. And even at 85% humidity, it is still dryer here.

 

 

Uhm so you grew up in 40C?

 

But yes it's interesting to see lots of literature suggesting eg 18C is some ideal sleep temperature, but then wrapping yourself in thick blankets so the effective temperature of your skin would still be (say) 30C? 

[SteamyTea]

9 minutes ago, puntloos said:

Uhm so you grew up in 40C

Far East.

When we moved to the West Indies we could cope quite nicely without A/C.