Passiv house summer overheating

just do it

Anyone with experience of this in an Irish passive house? Following modelling of my house with PHPP I need blinds to combat summer overheating. I know you can open windows but my design lends itself to fixed glazing. I've great views so I'm not over enamoured with the idea of pulling the blind on them on the few hot sunny summer days we get.

sydthebeat

can you consider a detachable 'brise soleil' type structure?

or even permanent one?

BryanF

provide external summer shading, above the window line of sight, think: pergola

fclauson

what percentage are you ober heating by - can you provide the figures from the first page of the PHPP calc

also what do you have in the summer ventalation tab

A fella called fish

First world problems..my house is too warm but I don't want to open my windows..

No6

Use suitable sun shading for the summer sun and you will not need blinds.

beyondpassive

Overheating is a big issue for Part L 2011, near Passive and Passivhaus. Its usually dealt with by a management strategy combining a number of approaches selected from the below list.
1. Increase nominal vent rate over 0.4 air changes or 75% fan speed
2. Plant trees deciduous trees or vines on a trellis outside.
3. rooflights or high level windows on actuators linked to BMS for purge
4. Blinds (internal)
5. Opening sections on windows open 25mm on security nightlatch for cross flow or stack ventilation.
6. brize soleil or awning, external shutters or blinds in the glass cavity. deep eaves in th edesign is the simplest approach
7. Purge fans at high level for overheating exhaust.

just do it

Solutions are based on two basic approaches: 1. shading, or 2. ventilation.

I note the following with interest:

beyondpassive wrote: »

deep eaves in the design is the simplest approach

What is the angle of the sun that we are trying to block? Surely the level of overhang required is an easy calculation based on this.

Also what is the effect of the glazing U-value i.e. 1.1 vs 0.8? Will a higher U-value this increase the level of overheating?

just do it

fclauson wrote: »

what percentage are you ober heating by - can you provide the figures from the first page of the PHPP calc

also what do you have in the summer ventalation tab

Don't have the excel to hand, just the report. There's just a mention of dealing with summer overheating using blinds. I've yet to discuss this with the architect but just thought I'd throw it out here for interest.

fclauson

just do it wrote: »

Solutions are based on two basic approaches: 1. shading, or 2. ventilation.

I note the following with interest:

What is the angle of the sun that we are trying to block? Surely the level of overhang required is an easy calculation based on this.

Also what is the effect of the glazing U-value i.e. 1.1 vs 0.8? Will a higher U-value this increase the level of overheating?

Now you are getting technical - there is more to glazing that U value - check a post of about 9 months ago where I talk about g value- which is the absorption of heat

Even this week when its +0 to 3 degrees the inside of my glazing is positivly warm from solar radiation due to the cloudless sky !!!

just do it

fclauson wrote: »

Now you are getting technical - there is more to glazing that U value - check a post of about 9 months ago where I talk about g value- which is the absorption of heat

Must do a search. I recall there being an extra element to getting passive certified windows other than U-value relating to solar transmittance (terminology could well be wrong). This no doubt is the same as the g-value you're refering to.

fclauson wrote: »

Even this week when its +0 to 3 degrees the inside of my glazing is positivly warm from solar radiation due to the cloudless sky !!!

as well as being warm, that must give a glow of satisfaction inside! It will be interesting to hear how the summer goes. Interestingly I've visited California a lot as I've family there and houses are designed to prevent too much light getting in with roof overhangs etc. There houses are designed to stay cool!

fatty pang

fclauson wrote: »

Now you are getting technical - there is more to glazing that U value - check a post of about 9 months ago where I talk about g value- which is the absorption of heat

Not quite...
g-value is a measure of solar energy transmittance.

just do it

Bump.

just do it wrote: »

Solutions are based on two basic approaches: 1. shading, or 2. ventilation.

I note the following with interest:

beyondpassive wrote: »

deep eaves in th edesign is the simplest approach

What is the angle of the sun that we are trying to block? Surely the level of overhang required is an easy calculation based on this.

Just to add the main windows in question are facing due south.

Anyone?

sinnerboy

Try this

just do it

How about a slight tint in the windows? Is this an option?

just do it

fclauson wrote: »

what percentage are you ober heating by - can you provide the figures from the first page of the PHPP calc

Now that I've the PHPP excels to hand it looks like overheating isn't going to be such a big issue: overheating percentage is 0.7% when I remove the reduction factor for blinds in the summer shading tab. I think we can live with that! Even if it proves to be an issue on an occasional fews days during the summer it will be easily dealt with as thanks to the design and coastal breeze it is easy to create a comfortable cross flow through the main living area (where the overheating is most likely to occur).

How does that % compare to yours?

Interestingly when I remove the shading factor from the near passive scenario (17.7kWh/m2/yr) the overheating figure is 2.6%. Another small reason to go passive?!

fclauson

my overheating is minimal - and I have big sliders - this pas week (prior to the rain) we had them open for 4 or 5 hrs !!!

no passive houses do not "EXPLODE" if you open a window or two