I am designing my house near Ipswich QLD. I have stunning views predominantly South. Secondary views to the East and SW. I know this is not an ideal orientation but that it what it is. I intend to build using SIP. The wisdom is that North facing windows are good for heat gain and South will result in heat loss in winter. This design premise seems based on poor thermal stability. However with full SIP construction where thermal stability is much greater, I believe that with low e-glass South facing windows this would be the most energy efficient design in a subtropical climate?
My plan is to have a long E-W orientation with the majority of the windows South. No windows West and a token window East. Rather than a compromise this seems the most sensible solution for a thermally stable SIP design. Have I missed something in my logic because I cannot find anything on the internet that confirms my idea?
Does SIPs help me change my South facing orientation?
(7 posts) (3 voices)-
bovine
MemberPosted Tuesday 6 Jun 2017 @ 6:31:34 am from IP # -
Benny
MemberWhat is "thermal stability" ?
"low e-glass South facing windows this would be the most energy efficient design" - I can't agree with that - doesn't it get cold in Ipswich in winter ? Your south facing windows will have very poor insulation compared to the south facing SIP wall that an efficient design would have. And with no windows facing N there'll be no free solar heating.
You could still make every attempt to make the house very efficient - design to 10 star etc - so it needs very little active heating - hopefully obtained form solar PV + heat pump heaters - but I can't see how you can claim your idea is the most energy efficient.Posted Tuesday 6 Jun 2017 @ 10:38:46 am from IP # -
d.darroch
MemberHow about north facing clerestory windows down the central spine of the house? These could light your southern rooms, & help heat them in winter (with the addition of some thermal mass that receives direct sunshine). They could also be opened on summer nights to help with purging of heat, & encouraging a breeze. Don't overglaze the southern windows too much. All windows are poor insulators. Double glazing would help with energy losses through conduction.
Solar PV is a good idea, design the roof for it.
Posted Tuesday 6 Jun 2017 @ 11:27:36 am from IP # -
bovine
MemberYes Benny it does get cold in Ipswich. For a month it gets rather chilly. Cooling in summer however I think is the key issue. North facing windows would be most desirable in winter but I was thinking of reducing the heat gain in summer. Appropriate Northen eaves will reduce the heat gain in summer so my idea was poorly formed. I was just trying to think how I can optimise my South facing orientation whilst still keeping lots of windows for the great views.
You are right - I still need to manage heat loss in winter at night from the South windows regardless of how efficient they are.
Thanks for the quick reply Benny.Posted Tuesday 6 Jun 2017 @ 11:31:54 am from IP # -
Benny
MemberInvestigate your energy use a bit more - many people in Aust - even here in Perth - spend more money heating their homes than cooling. Surprising I know but its there on the bills. Winter might not be severe but its usually longer than the summer cooling period.
For your windows yes, double glazing + very good curtains inside - its going to be expensive for that view!Posted Wednesday 7 Jun 2017 @ 12:32:13 am from IP # -
bovine
MemberThanks d.darroch. I too was drawn to the clerestory windows as a solution to my natural lighting issue but I am unlikely to be able to be able to incorporate thermal mass due to the hillside lightweight construction. Clerestory windows may suffer from heat loss at night when I most want to retain the heat. The lack of thermal mass means that clerestory windows only provide benefits in the daytime when the temperatures are a tolerable 15-20 degrees C. So this doesn't appear to be a clear solution. As I will have off-grid power then LED lighting will be be a practical solution to boosting lighting for my south facing windows during the day.
My green alternative that minimises my battery storage demand is to create insulated shutters for the bedrooms. Shutters will not be practical solution for the open space living areas so I have a morning heating issue in this area. I had wanted to use solar water heating as uses little stored battery power. The set up costs for the solar water/oil radiators seem prohibitive in Brisbane.
In essence I am trying to identify as many strategies that can use to deal with the constraints of poor site orientation, lightweight construction and off-grid power limitations.Posted Saturday 10 Jun 2017 @ 1:07:41 pm from IP # -
Benny
MemberI agree if you don't have thermal mass there's not much point in letting in the solar radiation.
Also agree that with LEDs using so little power and cheap PV there's little point using "natural" lighting - other than provided by the windows of course.
As the "lots of solar input + high thermal mass" solution seems to be too hard for you then I agree you go for the "low thermal mass + heaps of insulation" strategy. Live in an esky (-;
You'll need active heating but it should be minimal if you really insulate those windows and get high performance split ACs. There are options where US houses have large polystyrene panels outside - especially if its a downhill slope - and these "shutters' are closed at night. If you have curtains / blinds inside you won't see them. Unless you want the view at night too ?Posted Sunday 11 Jun 2017 @ 1:28:24 am from IP #