Preliminary plans have arrived

[Robert Clark]

Hi Guys

Have just received preliminary plans for our new build Passivhaus 

 

Any comments or suggestions would be appreciated 

 

Thanks 

 

 

 

 

[ToughButterCup]

Interesting. Looks very well thought through.

First, compliments on the use of colour - makes the plan much easier to understand.

Only one comment about the plan; consider changing the southern dressing room to a mezzanine ..... ?

[Mr Punter]

Very nice plans.  I would be concerned with overheating and would want this modelled.  The proposed overhang does not look like it will mitigate this. The lounge looks the most vulnerable.  Hoping that is not a wood burning stove in the lounge as this is at odds with clean, modern living and if the house is properly insulated it would need to be minute to prevent overheating, even on a cold, cloudy day.

[epsilonGreedy]

It would be useful to have the calculated internal floor area.

 

The design incorporates some wow features with its baronial dining hall space and dedicated gym. I hope the internal gym wall will be mainly glazed to connect it with the hall area.

 

I feel the kitchen is undersized for a property of this stature and the lack of a walk-in utility room and preferably a pantry is a major miss for me.

 

I have some specific observations on the sitting room having lived in a property with a similar size room and with the internal door in the same position. The double focused furniture arrangement does not work and actually caused interpersonal schisms. I would loose 3ft of glazing on the west wall to allow the stove to be centered further south on that west wall as this will promote a central furniture arrangement.

 

Have you and your architect experimented with larger eve overhangs? What about wide plank timber cladding?

 

Have you or your architect lived in North America, I ask because there seem to be some design choices inspired through living in another culture. 

Edited January 17, 2019 by epsilonGreedy

[Bitpipe]

Lovely house aesthetically but +1 on the WBS & solar overheating.

 

Was snowing this morning and as I ran the hoover round in my t-shirt I was already feeling warm in our Passive standard house. UFH (ground floor only) has barely come on this winter at all.

 

You have a massive south facing window in the dining hall which will make it very uncomfortable year round unless you use external blinds or apply a reflective film to the glass.

 

On our build, purely by virtue of the plot orientation,  we minimised south and north glazing. After a few months in an overheating caravan in the garden we specd external motorised shutters on the east windows (wall and roof) - omitted one south window in kitchen and in spring and autumn when the sun is low, it really heats up.

 

West glazing is not as susceptible but still makes an impact in summer- we have internal lightweight drapes that reduce the effect but will probably build a bris soleil to give us a bit more shade.  

 

If your architect has considered these elements then it would be a bit of an alarm bell as to whether they understand the implications of building a well insulated, airtight home (whether passive standard or not).

 

Get it modelled in PHPP or equivalent.

 

 

 

[Robert Clark]

3 hours ago, Mr Punter said:

Very nice plans.  I would be concerned with overheating and would want this modelled.  The proposed overhang does not look like it will mitigate this. The lounge looks the most vulnerable.  Hoping that is not a wood burning stove in the lounge as this is at odds with clean, modern living and if the house is properly insulated it would need to be minute to prevent overheating, even on a cold, cloudy day.

Thanks for your feedback 

The Architect is Passivhaus certified and as such the building will be modelled using the passive planning software not to overheat.

The log burner is a passive type with a very low output to the room.  It puts almost all its output into water and will supply a thermal store for heating and hot water. 

[Robert Clark]

2 hours ago, epsilonGreedy said:

It would be useful to have the computed internal floor area.

 

The design incorporates some wow features with its baronial dining hall space and dedicated gym. I hope the internal gym wall will be mainly glazed to connect it with the hall area.

 

I feel the kitchen is undersized for a property of this stature and the lack of a walk-in utility room and preferably a pantry is a major miss for me.

 

I have some specific observations on the sitting room having lived in a property with a similar size room and with the internal door in the same position. The double focused furniture arrangement does not work and actually caused interpersonal schisms. I would loose 3ft of glazing on the west wall to allow the stove to be centered further south on that west wall as this will promote a central furniture arrangement.

 

Have you and your architect experimented with larger eve overhangs? What about wide plank timber cladding?

 

Have you or your architect lived in North America, I ask because there seem to be some design choices inspired through living in another culture. 

 

Thanks for your feedback - some great ideas!

We has the same thoughts about the larder and have incorporated this into the kitchen, behind the sofa.

We have also removed the wall between the kitchen and the dining hall to make one larger space.

We are using charred timber cladding in some areas, hopefully this will show up better on the next set of drawings.

Like you we think that the lounge is too big, so have moved the WC and Plant Room into the rear of the lounge, giving us a bigger boot room and allowing us to move the fireplace to a more central position.

 

 

Edited January 17, 2019 by Robert Clark
Missed bits

[Robert Clark]

2 hours ago, Bitpipe said:

Lovely house aesthetically but +1 on the WBS & solar overheating.

 

Was snowing this morning and as I ran the hoover round in my t-shirt I was already feeling warm in our Passive standard house. UFH (ground floor only) has barely come on this winter at all.

 

You have a massive south facing window in the dining hall which will make it very uncomfortable year round unless you use external blinds or apply a reflective film to the glass.

 

On our build, purely by virtue of the plot orientation,  we minimised south and north glazing. After a few months in an overheating caravan in the garden we specd external motorised shutters on the east windows (wall and roof) - omitted one south window in kitchen and in spring and autumn when the sun is low, it really heats up.

 

West glazing is not as susceptible but still makes an impact in summer- we have internal lightweight drapes that reduce the effect but will probably build a bris soleil to give us a bit more shade.  

 

If your architect has considered these elements then it would be a bit of an alarm bell as to whether they understand the implications of building a well insulated, airtight home (whether passive standard or not).

 

Get it modelled in PHPP or equivalent.

 

 

 

 

Thanks for your suggestions 

Our Architect is Certified Passivhaus Designer and is using the PHPP modelling software.

Like the idea of the external motorised shutters !

[jack]

24 minutes ago, Robert Clark said:

Like the idea of the external motorised shutters !

Another one here with motorised external shutters. Good for privacy and exceptional for reducing solar gain, but don't rely on them for keeping rooms dark. 

 

36 minutes ago, Robert Clark said:

The log burner is a passive type with a very low output to the room.  It puts almost all its output into water and will supply a thermal store for heating and hot water. 

 

I still suspect you'll roast! Anything more than two people in our TV room (equivalent to a few hundred watts at most) results in uncomfortable local temperatures within half an hour. What's the room output on the burner you're looking at?

[Robert Clark]

18 minutes ago, jack said:

Another one here with motorised external shutters. Good for privacy and exceptional for reducing solar gain, but don't rely on them for keeping rooms dark. 

 

 

I still suspect you'll roast! Anything more than two people in our TV room (equivalent to a few hundred watts at most) results in uncomfortable local temperatures within half an hour. What's the room output on the burner you're looking at?

 

Looks like the minimum output to the room is 1kw

 

https://www.stovesonline.co.uk/wood_burning_stoves/Woodfire-Passiv-Boiler-Stoves.html#entity_10213

[Mr Punter]

If you choke the stove down to 1kW it will be very inefficient at combustion, so higher emissions.  Even at this level you will swelter. The nominal output is 3kW, so good for a sauna.

[Alex C]

I have a passive spec house and agree with all the points made above by others that do as well. Your architect may be qualified to design a passive house but if he dosn't actually live in one he may not fully appreciate things like the risk of overheating  from sun and fires. There is no way you will ever use a log burner. Your south facing double height glazing will massively overheat the room. The brise soleil as drawn will do nothing except for a couple of weeks around the longest day when the sun is really high in the sky. A normal rule of thumb with brise soleil is to make them protrude from the build by half the height of the glass they are shading. Even this would have overheating issues in spring and autumn. You have quite a good roof overhang on the south side to shade bedroom windows in mid summer, this will be helped more if you recess the windows well back into the wall. Even so the bedrooms are likely to overheat without any external shading. External venetian blinds as used by others on this forum and also myself are not an expensive luxury but a necesity in a passive house with lots of  glazing. I would also worry about your lounge cooking in the evening late summer sun Bed three and four will have a real issue as there is no cross ventilation in these rooms to purge at night . I assume windows on master and guest open on north and south elevation to provide cross ventilation? My experience is that night purging with a large roof light works really well in an open plan house, but useless if it isnt open plan or you shot your doors. I would also suggest getting rid of the sun tunnels. You have. passive spec house, then are making 14" holes in it with an uninsulated tube. Budget for some quality light fittings instead. I would suggest that for such a grand house the corridor on ground floor is way too narrow. I think it is also a massive mistake to make your dinner party guests leave the grand dining hall and squeeze past your muddy boots to take a pee. Generally I think it looks a really interesting build and I'm sure will be a lovely place to live. 

[Alex C]

A thought on your cladding. I looked extensively into using charred timer. The black charring will wash off over time and the timber will silver. This may be good or bad but don't think your house will stay looking a nice solid black colour. As an example look at the grand designs house of the year beside the loch. It is no longer black at all as all the charring clearly got washed off by the rain.

[Jeremy Harris]

As if on cue, today has provided a good illustration of the way a passive house can overheat during spring and autumn, or even winter.

 

Today has been bright and clear, and despite the shading overhang over our south-facing glazing (which does nothing at all at this time of year), despite the fact that our heating hasn't come on at all for the past two days, and despite the fact that we have heat-reflecting film on the outside of our east and south-facing glazing, our house reached well over 24 deg C early this afternoon and the cooling system came on for a couple of hours.  The outside air temperature didn't exceed 8 deg C all day, and was around 7 deg C when the cooling system came on.  The house is now just under 23 deg C, still a bit warm, but we would have been in for an uncomfortable night if the cooling system hadn't come on for a couple of hours and cooled the bedrooms down to below 20 deg C.

 

We have suffered from the house getting a bit too warm in the spring and autumn, when the sun is low in the sky and penetrates deeply into the house, bypassing the shading, but I can't remember the cooling system having to come on in January before.  The saving grace was that our PV system was generating a fair bit of power all day, more than enough to run the air-to-air heat pump that is built in to our MVHR system and which provides comfort air cooling.

 

So. to sum up, I think your design definitely needs some better shading on those large glazed areas that face south, if you are not to suffer the same sort of problems that we've had to deal with.  I modelled our house in PHPP, and accepted a small overheating risk, without realising that any overheating risk shown in PHPP can be unacceptable, because of the very long thermal time constant of the house, which is a consequence of having a long decrement delay structure and low heat loss rate.

 

[Alex C]

@jsharris couldn't you just open a window rather than having to run a cooling system?

Our living room got pretty warm today as we have quite a bit of south facing glass as well. I generally don't mind this in the winter as the house is open plan the excess heat tends to disapate around the house and not be a problem. The heat absorbed into the slab today will keep the house warm for the next few days with no additional heating requirement at all.

Edited January 17, 2019 by Alex C

[Bitpipe]

6 minutes ago, Alex C said:

@jsharris couldn't you just open a window rather than having to run a cooling system?

Our living room got pretty warm today as we have quite a bit of south facing glass as well. I generally don't mind this in the winter as the house is open plan the excess heat tends to disapate around the house and not be a problem. The heat absorbed into the slab today will keep the house warm for the next few days with no additional heating requirement at all.

 

In an airtight house, opening one window does not make much a difference, you need to create a cross draught. You're also supposing that the external air is cooler than the internal air.

 

True at this time of year but not in the summer...

[ProDave]

I share the stove concerns.  That lounge would overheat very quickly.

 

We do have a stove and we do use it, but our kitchen / diner (similar size to your lounge) opens with double doors straight to the stairwell, then double doors the other side to the lounge.  With all doors open it is pretty much the whole ground floor open, and a stairwell to let heat upstairs.  Like this with everything open, the stove can be used carefully. 

 

But in your lounge, with little obvious route for it to heat the whole house, I think you would kust overheat that room very quickly indeed.

[Jeremy Harris]

10 minutes ago, Alex C said:

@jsharris couldn't you just open a window rather than having to run a cooling system?

Our living room got pretty warm today as we have quite a bit of south facing glass as well. I generally don't mind this in the winter as the house is open plan the excess heat tends to disapate around the house and not be a problem. The heat absorbed into the slab today will keep the house warm for the next few days with no additional heating requirement at all.

 

Just as @Bitpipe says, opening a window doesn't do anything much, and creating a cross-draft by opening windows at either end of the house works, but tends to make rooms that aren't too hot a bit cooler than needed.

 

With the MVHR in active cooling mode (it switched to 100% bypass and passive cooling mode a couple of hours earlier, I think) it tends to preferentially cool the bedrooms, as i've set those up to have a fairly high flow rate.  This is ideal for cooling, as cooling the first floor (which doesn't get much direct solar gain) tends to limit the amount of heat that rises from the large entrance hall space, as long as we keep the bedroom doors closed during the day.

 

The other point is that I don't want to have to faff around opening or closing windows, so the house systems are set to regulate the environment without me needing to twiddle with anything.  The cooling is set to come on when the upstairs landing reaches 24 deg C, and at first it will try to passively cool by just switching to 100% bypass and feeding cool air from outside into the house at a low flow rate (the normal background ventilation rate) and if the temperature continues to rise the MVHR will automatically increase the fan speed, then turn on the air-to-air heat pump.

[Alex C]

I designed my own passive spec house to have at least 2 opening windows on different elevations in each room (but only 1 in my office as it has rooms on both sides) and also with 2 large roof lights at the top of the open plan landing that open automatically at 25 degrees c. This makes purging heat in any room really easy as opening a window in the overheated room moves the heat outside in just a few minutes. There aren't that many times a year that opening a window at night dosen't cool a house down. This is all pretty standard stuff and is something any architect should be looking at doing in a new build.

[Jeremy Harris]

But why have to open windows, letting in bugs, unfiltered air, etc, when the MVHR can just do it with no reduction in air quality or need for any form of intervention?

 

We do have opening windows in every room, but never bother to open them.  One reason is that we're in the countryside and plagued by cluster flies whenever the sun warms up the outside of the house, so the last thing I'd want to do is open a window and have a house full of flies within a few minutes.  The cluster fly problem goes away by late spring, but then so does the overheating problem.  Sadly the cluster flies come back in autumn, just when the house is prone to occasional overheating again.

[Alex C]

The windows hardly every need opening. I am just talking about a basic principal of cross ventilation and night purging. The op's architect has incorporated this as well by having an automatically opening roof light. I understand there are other ways to help cool a house, but none quite so simple or fool proof.

[Jeremy Harris]

I take your point, but assume that you aren't plagued with cluster flies!

 

This is the second house we've owned which has been a magnet for the damned things, and we've learned over the years that there isn't anything much you can do about them, other than not open windows and open and close outside doors as quickly as possible when going in or out during cluster fly swarm periods.

 

From all I've read up on cluster flies over the years, I've not seen anything that's a reliable predictor as to whether or not a given house will attract them.  Our neighbour on one side never has a problem with them, the neighbour the other side has much the same problem as we do.  Once they decide they like a house they will keep coming back, pretty much no matter what you try to do to dissuade them.  This leads me to believe that relying on having to open windows to get ventilation at the design stage may not be wise, as there is no way of telling at that point whether or not the house is going to be a "cluster fly magnet", other than, perhaps, if it's in the middle of a large town or city, where the damned things don't seem to be a problem.

[Sue B]

Fly screens!  After 10 years in a house backing into a canal I heartily recommend fly screens.  We retro fitted a year after our build was complete last time - this time we are planning then in from the start.

[Robert Clark]

Thanks for the feedback and suggestions so far.

If we scrapped the log burner, what would be a good heat source where natural gas is not available?

 

[Alex C]

We are next to fields and I think they put so many chemicals on them there aren't many flies left. We just seem to have a week a year when tiny storm bugs get everywhere, oh and also the ladybird invasion before Christmas, definately no window opening then.