Passivhaus form

[Nick Grant]

Curious in anyone has managed to achieve 15kWh/(m2.a) in PHPP for a single storey school building.

Seems quite hard given the poor surface area to volume ratio.

Any leads would be most welcome.

Nick

[Mark Siddall]

Hi Nick,
I don't think that you can get much worse than bungalows...... which is one of the the PH schemes that I'm working on. So on this basis I'd say that it is achievable but challenging.

The U-values might be lower than you may normally expect ....but in a school you could easily focus on an easy win by turning attention to the air leakage. (As an n50 of 0.6, in a large buildings, can result in greater infiltration that would be found in a house (surface area to volume issue) you could target the AECB 0.75 m3/m2@50pa and see what the resultant n50 value is. The reduced ventialtion losses should relax the U-value requirement.)

Cheers,
Mark

[Nick Grant]

Thanks Mark, good points and gives me hope. Your bungalows are terraced though which helps.

Cheers

Nick

[Mark Siddall]

Yes terracing helps. At 67sqm/ unit (net internal), the shortest terrace is 5 unit long i.e. 335sqm (7.85m deep internal dimension). I'd imagine that a small school should easily have an internal area greater than this.

Mark

[Dave Howorth]

Pure curiosity but how does PHPP handle non-domestic buildings? There's no requirement for temperature control outside working hours and in the case of a school there are periods of several weeks where control isn't required. Doesn't matter if it overheats in summer, for example (unless it also serves as a community hall or something).

I was interested to look at an evaluation of various types of renewables for a school recently. Solar thermal came out as a clear winner and that was despite all the energy for the best two months being ignored as there was no useful purpose in an unoccupied building.

Presumably you also have a lot more internal heat gains in a school than a house. A bit like the 50 W dog. If it starts getting cold, get the kids to run around.

[Nick Grant]

Hopefully Alan can give a fuller answer but I'd say phpp handles schools quite simply.
Phpp looks at the energy ballance of the whole building and assumes it is all at similar temperature.
It is known that gains from kids are more than the peak heat demand so heating is by small rad not ventilation air or under floor. Heating can go off as soon as kids enter classroom.

As with any model you could design something that gave the right results but didn't work-it is a tool not an autonomous designer.

Curious what you say about solar. Do you mean works in energy terms or economics?

If no showers then I'd look at local electric heating and spray taps. Need to do the numbers of course.

Sorry about any typos as this is from phone and I can't seem to scroll to top.

Nick

Nick

[Dave Howorth]

Thanks Nick. I took a look at the PHPP manual and see that flexibility/discretion is the watchword.

The solar thermal worked best in terms of meeting the planning requirement at least cost. The main demand is from the kitchens.

Your typing seems fine and at least it doesn't have one of those annoying 'sent from my iPhone/Blackberry' signatures.

Cheers, Dave