Minimise E &W glazing but avoid solar control glass as this will spoil winter heat gain!
We have no direct E/W windows, but unfortunately due to the orientation of the plot we have large SE/NW windows. Most of them now have some form of shading to help in the worst of the summer.
Internal blinds not much use (unless very reflective?), need external for overheating.
I've just been using the temporary shading figures quoted in the PHPP manual. I agree they're not great for internal blinds but do enough to get that last 1% if it turns out to be needed.
Night vent and thermal mass assumptions critical.
It's a high thermal mass build, which helps a lot - I'm using 180Wh/m2.K in PHPP. I'm being reasonably pessimistic on night ventilation - we could certainly open more windows to help out whne the house is occupied.
Where are you located? What weather data are you using?
Good point. I'm based in North Wiltshire, but am currently using weather data from Manchester, (but with accurate position/altitude data) which is the only data set in PHPP with full weather data. If there's a reasonable way I can get more accurate data then I'd be very interested to use it.
Optimise rooflights for daylight and no more.
Any guidance on optimising for daylight? I'm not really sure how to estimate what we are going to need, so I'm just running with the architect's proposal, but with no way to validate if it is right or not. It feels about right, but I'm not sure how to determine if 100mm smaller would be OK or not.