Hi All

I'm planning an energy efficient, airtight home using SIPs along with MVHR, triple glazed windows etc.
I'm worried about overheating issues arising in the summer months. Please can someone advise of the best methods to minimize this issue.
Any replies much appreciated.
regards
Jaz

Trust your architect.

Summer shading.

Some form of feature (louvres, planting, whatever) will help a lot with reducing solar gain in summer.

If it were me, I would design in passive solar for winter and the shoulder months, with a nice overhang or feature to prevent solar gain in summer. A dense concrete block internal spine wall that catches winter sun would also help to maximise winter absorbtion, and provide some control of internal temps in the summer.

Having said that, there are many many people across the world who live in timber frame houses (similar in terms of thermal mass) who make it work. The rest of the world can't be wrong...... can they?

Also, as an addition to the comment above about opening a window, think about through ventillation of windows, i.e. make sure that you can throw a few windows open on oposite sides of the house to get some decent cross ventillation in summer.

no

you ca use night time cooling or sort the MHRV with a summer bypass

physical shading is the best answer

Some lightweight houses in more northerly locations than the UK regularly overheat in winter too

I have wondered, actually, on the thought of an internal spine wall, what about building in deliberate thermal bypass. I.e. build a twin leaf dense concrete wall and introduce deliberate and controlled air movement into the wall.

During the winter the cavity would be blocked off with insulated closers and solar gain absorbed into the wall (perhaps allowing internal air into the void to promote convection on warm air). In the summer the bottom and top of the wall could be opened up to external air to promote night time cooling of the spine wall?!

I think it would work, but be very dependant on actually controling the air movement within the wall cavity!

Timber

Posted By: Timberbuild a twin leaf dense concrete wall and introduce deliberate and controlled air movement into the wall.

Something similar is already being done - unintentionally
http://www.dailymail.co.uk/property/article-1336116/The-new-homes-fail-energy-tests.html?ito=feeds-newsxml

(Thanks to @sebvandort of http://www.dailygreennews.co.uk/ for tweeting this, and @GeoffWilkinson for retweeting)

Timber, the Winter/Summer dichotomy would be solved by the angle of the sun. Summer overhang shading and low mass walls means no heat build-up or problems from decrement delay. Winter sun coming at low angles is under the shade barrier and heats your spine wall. No need for the cavity. Simples.

Mark

I am with you on that one and a simple spine wall is, well, simple.

But you know people and the need to over-complicate things!! Plus I think it is an interesting idea in turning a passive process into a more actively controlled process.

Timber

Timber: there's a good argument then for masonry internal walls in a timber frame with low mass external walls. The masonry would act to stabilise the internal temperatures. Looking at that particular scenario right now, the only need that would arise in the design is in the founds to support the differing mass of masonry against the original concept of dry-wall. Interesting line of thought. Note DarylP that I am talking about stabilisation, not particularly about gaining winter solar heat (which involves a glazing issue).

Am I re-inventing the wheel?

ST: the question is, is your control active or passive?

Back to the drawing board.

(Or this new-fangled AutoCad. )

Jazgill,

taking on board the shading ideas above, pehaps you could design in some strcutural supports in the zones above the window openings, so that shading (brise soleil) could be applid later, once you have lived in the house, and experienced a summer. SIP's (as I understand them) won't have great "pullout" resistance unless additional structure is design-in.

Since the shading detailing, does not always look that great on a dometic property (can look great on large office blocks etc), it could be a detatchable system, for example on the ground floor only if that was where most of the glazing were installed? What about a balcony (2 small balconies) over the glazed openings? I've just done that for my own "passive-style" house.

GreenPaddy.