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Design Dilemma
brett_webster9777901

Solar passive advice please

Brett Webster
8 years ago
Hi all. Am building a house in Berridale, a short drive from the Snowy Mountains.

It will be brick veneer, colour bond roofed home and insulated as best I can. Will also have double glazing and a bare slab in the living area.

For supplementary heating I'm considering a heat pump but have left space in the living area between the two large windows for a wood heater just in case. I'd really appreciate it if those in the know could review the floor plan below to see if there are any glaringly obvious faults. Many thanks in advance :-)

Brett

PS. I know the western window isn't ideal but the cats will love it and I will externally shade it in summer.
Featured Answer
  • jbantick
    8 years ago

    kitchen, dining, living to the sunny side.

    bathrooms, laundry to the cold side.

    bedrooms to east or west but the living areas are still to get as much sun as possible.

    hydronic in slab heating is good but needs heating by a cheap method. so look at solar with boost from a wet back stove/heater. electric is ok but PV panels would make a big difference to the power bill.

    double glazing is good but works even better on the cold side of a house (for bedrooms, bathroom, etc.) so once the hydronic heating has warmed the slab double glazing is brilliant at keeping the heat in. If you can't afford hydronic heating at least add the pipes into the slab before pouring. You have the option in the future when the mechanics of it become cheaper!

    The pipes are quite inexpensive.

    Double glazing is relatively cheap if you shop around. Small manufacturers are usually just as inexpensive and of a higher quality than the big well known manufacturers. Some big manufacturers windows are under performing low efficient crap!! Just spec the double glazing up front!

    insulate everywhere including the slab edge!

    reverse brick veneer is good but is really good if it can be warmed by the sun in winter.

    Comments (41)

    • Brett Webster
      Original Author
      8 years ago
      Should have added in case this goes international, it's in Australia.
    • PRO
      OnePlan
      8 years ago

      its landed in the UK thread !

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    • Brett Webster
      Original Author
      8 years ago
      Cheers OnePlan, so reverse the orientation and comment away!
    • Emily
      8 years ago
      Love the layout in general, looks great. I only thing that would concern me is having the laundry where it is. If you have the washing machine going on one side of the wall and you're trying to watch tv on the other, it might be a bit of a pain. I would personally rotate the living room so the seating is facing outside, give the living room a bit more space and put a tv on the wall reserved for the wood heater. Would make better use of the, I'm assuming, great views you have, and you wouldn't have to walk in front of the living to get to the laundry. If the laundry doesn't bother you though, then it's a great layout :)
      Brett Webster thanked Emily
    • Brett Webster
      Original Author
      8 years ago

      Thanks Emily, I actually did have the living area configure the way you suggested it but change it due to reducing the size of the wall between the windows. I can push the windows out thought which would probably give enough space for the TV/possible wood heater. Will post a revision tonight

    • Emily
      8 years ago
      Another advantage of moving the lounge would be that you could move the door to the master bedroom so that it comes off the other wall, giving you more kitchen wall space for cabinets etc.
    • Brett Webster
      Original Author
      8 years ago
      Like this? I had it this way before but changed it around to get bigger windows in the living area for solar gain. This has shrunk the windows to 3 metres in length each which puts me on the lower limit for glass:slab ratio.
    • Emily
      8 years ago
      I personally think that looks and flows better, a wood heater would be a great feature there. I've never built a house before so I don't fully understand the glass to slab ratio, could you explain it please?
    • Brett Webster
      Original Author
      8 years ago

      From what I've read if you're looking to use the slab as a solar passive heat source you need to have a ratio of North facing glass (in the Southern Hemisphere) to slab of at least 12.5%, more in colder areas such as where I'm building.


      In this design, not including the bathroom and laundry windows I've got 12.6 square metres of glass (2 windows @ 3.0 metres x 2.1 metres). The slab is roughly 110 square metres so my glass:slab ratio is around 11.5%.


      Would be nice if someone could chime in on whether the bathroom and laundry windows would help overall even though they're not in the living area.


      I agree though the second sketch does flow better, it may be a sacrifice I'll have to make in order to make the best use of the space.

    • Emily
      8 years ago
      Okay, that makes sense. I can't see why they wouldn't count, they're still North facing windows. Could you extend the height of the windows?
    • Emily
      8 years ago
      Also, why do you need to increase the size of the wall between the windows for the second layout?
    • Brett Webster
      Original Author
      8 years ago

      Height of the windows is fixed unfortunately, going higher may well blow the budget. The wall is wider so I can fit a big TV , speakers etc.

    • Emily
      8 years ago
      Hmm, only thing I can think of is having a freestanding tv etc so the wall can be smaller. Have you done the ratio math including the other small windows? It's a tricky situation. I definitely prefer plan 2 but understand the need for the house to be thermally efficient given where you live
    • Brett Webster
      Original Author
      8 years ago
      With the bathroom and laundry windows included it would be over 13%. Problem is they're not floor to ceiling so I think the solar gain would be reduced. Perhaps a full glass laundry door would be worth looking into (pun not intended).

      I don't think a freestanding TV thing would work.
    • PRO
      OnePlan
      8 years ago
      Stick with the central lounge area and put your TV on one of these so you can keep the larger openings for heat and light - with one of these TV stands you can watch TV indoors or outdoors on nice summer evenings
      http://houzz.com/photos/162391
    • Angelina
      8 years ago
      Add insulation batts to the internal walls separating the laundry and ensuite from the living area. This will act as a sound barrier so you won't hear noise from these rooms when you at sitting on the couches.
    • Emily
      8 years ago
      http://www.yourhome.gov.au/passive-design/thermal-mass

      Not sure if you've checked out their website but very helpful. From what I've read, those smaller windows will count towards the glass slab ratio. I've had another thought, do you have any skylights in your current design? Not sure if you have a sloped roof or not, if the skylights could face North even better but if not surely they'd still help bring light and heat in?
    • Brett Webster
      Original Author
      8 years ago
      Thanks Emily yes I've been all over that sight a number of times. There are conflicting figures all through it regarding the amount of glazing (also whether or not the entire slab should be insulated or just the edges) which is a little unhelpful but it does address solar passive principles well.

      I'm hoping the builders architect will be able to confirm the effectiveness of the design, the builder is an old school guy who doesn't seem to be up to speed on solar passive design (which is a concern given the area he operates in), but he does build quality homes.
    • fianou
      8 years ago
      last modified: 8 years ago

      If you are having a slab floor than laying hydronic coils in the slab for heating is the way to go... otherwise your floor will be freezing cold in winter! It will warm a lot but you will probably need a wood fire also. Wood fire will create a much longer lasting heat that will be stored in your thermal mass also. Also spring for decent double glazing or you will end up with crying windows.

      In terms of letting in light for solar gain in winter... actually there are a few issues I can see. Because your living area is enclosed on both sides by bathrooms it will limit the time you have to warm the house by sunlight. You will only have a short time when the sun is passing across the northish side of your place. You want the morning sun to stream in and heat the slab so need to open to the east a bit more. I would place the open kitchen area to the top right corner of the house instead of laundry. The placing of both your laundry and your bathroom on both those corners will make it cold and dark in the living area for large chunks of the day. You will lose the light so early and it would only come into your living areas by late morning. Your kitchen will always be fairly dark if on the south side. I would swap the laundry and bathrooms to the south corners. I would screen the north west side with deciduous trees to maximise solar gain in winter but shield from extreme heat in summer. Also paving outside the house on the north side will extend the thermal mass. By placing the master suite at the west it will take in the last warmth of the day in winter just before you need it. I would add a tv lounge to the south east corner, because you don't want direct light for a tv and it will be a cosy living space. Your kitchen will be filled with light in the morning and be the hub of the more formal and informal living areas. Excuse the rough drawing, but something like this(click the picture to see the full drawing, I don't know why its cutting it off so much):

    • Brett Webster
      Original Author
      8 years ago
      Thanks fianou. Some food for thought there.

      I do plan on double glazed windows and would love hydronic heating but I don't think I can fit it into the budget.
    • fianou
      8 years ago

      You may need some other floor coverings over the slab, if that's thick rugs you pull up in the summer or full laid floor coverings. The polished concrete will be too cold in winter.

    • Brett Webster
      Original Author
      8 years ago
      Thanks again fianou. I was planning on a couple of rugs anyway, but you make it sound as though I'll get no benefit from the sun hitting the slab at all. Have I completely misunderstood the whole thermal mass/solar passive thing here?

      The site has very good solar access, the living area faces approximately NNE. With double glazing and good insulation (including at least the edge of the slab) I was expecting the slab to retain some heat into the evenings on good days. Obviously on overcast days it will be cold underfoot but I'm not one for walking around barefoot in the cooler months anyway.
    • fianou
      8 years ago

      Yes your slab will retain some heat, but likewise it will retain cool as well, particularly the cold under the floor from the earth itself. So early morning it will be quite cold under the feet as the slab would have given off all the heat it would have captured and stored during the day.

      However, it will also retain heat from other sources like your fireplace, which is a bonus. As long as you get the full sun on the slab it will store some heat, but with the corners blocked in with rooms it will limit the exposure to the sun. Its all about capturing the most sun, especially when its low in the sky in winter. You WILL get a lot of benefit from the sun hitting the slab, but it won't be enough to keep you warm. Passive solar gain is not a way to heat your house but it minimises the need for external heating/cooling systems. It keeps your house temperatures more stable. As far as I understand.

    • PRO
      Envirotecture
      8 years ago

      I'd suggest moving all your daytime occupied areas to the north side, locating a laundry and bathroom in the best locations is a odd choice (unless i have missed something about other site constraints).

      I would suggest not building in brick veneer, it will not help your thermal performance at all.

      If you install hydronics you will not need any other heating source. If you install sufficient PV you will get free heating for life (once you have paid the up front installation costs).

      Building in the Snowies you will get great benefit from good quality double glazed windows, either timber or thermally-broken aluminium frames.

      If you want to understand how your building will perform then get a professional thermal assessment done. You will be able to ask questions and run various 'what -ifs'. You can also use the final results fro you BASIX certificate that you will need.

      Hope this helps

    • Brett Webster
      Original Author
      8 years ago
      Thanks all for the constructive comments. Have taken them on board and ended up with a more useable space I think.

      Revision below. The entry is a bit awkward but a diagonal corner in the adjacent bedroom might help there. I've put the master suite on the eastern side because the view's slightly better, plus I'd rather sleep under icicles than a ceiling fan. Looking forward to further critique
    • Emily
      8 years ago
      Hey Brett, is the location of the entry movable? Seems like as long as it's where it is and your main living areas are on the north side there will be wasted space as a hallway.
    • Brett Webster
      Original Author
      8 years ago
      last modified: 8 years ago

      I could move it around the side but it would then mean laundry access issues. Also to get to the entry if it was near the lower corner of the TV space it would be a bit of a treck around the garage and up the side of the house.

    • Brett Webster
      Original Author
      8 years ago
      Awkward entry into living area solved by relocating the kitchen?
    • Emily
      8 years ago
      I was thinking about that, definitely an improvement I'd say. Closer to the light, and you can have more cabinet space along the right hand corner of the North wall if needed. Win win :)
    • Emily
      8 years ago
      Just spotted the location of the door to master bedroom, could you move the fitted wardrobe (I assume that's what it is) and have the door off the entrance hallway?
    • Emily
      8 years ago
      If you can solve that problem then I can't see any others, given what you're trying to achieve with the passive heating systems this seems to be the most efficient layout I can think of, and I've been thinking for a few days now haha. I hope it all works out for you, I'm really passionate about what you're trying to achieve and I can tell you are too :)
      Brett Webster thanked Emily
    • Brett Webster
      Original Author
      8 years ago

      I fixed it some more. Reduced the length of the kitchen slightly so it fits back in the original location without cramping the entry into the living room (it's now about 1200mm wide). Makes the entry into the master bedroom a lot better too.


      Thanks for the positive comments Emily, sorry if I've ruined your concentration on other things

    • Emily
      8 years ago
      Haha don't be sorry, I love trying to solve problems. Looks great Brett, I'm sure it will be a really lovely (and hopefully warm!) home. Good luck with it :)
      Brett Webster thanked Emily
    • bargainhunter
      8 years ago
      I agree with Emily re moving bed 1 door. I'm not a fan of bedrooms directly off living area
    • baysig
      8 years ago

      Hi Brett. Just wanted to congratulate you. We have lived in an architecturally-designed passive solar house for 5 years now and love it. (It was built in 1989, so a bit before it's time!) It is noticeably cooler in summer and a lot warmer in winter. The power bills are less - and less again now we have solar panels on the roof. Our next property will definitely be passive solar design also. (Just a tip....if you are going to have a covered entertainment area/patio attached to the house at some point, it is well worth saving for the Danpalon - or similar commercial brand - roofing. The cheap polycarbonate sheets are really hot. The commercial grade ones do not let 95% of the heat through....but do let 98% of the light through. You can use the area most of the year then.....and it won't affect the light coming into the house.) Good luck!

      Brett Webster thanked baysig
    • Brett Webster
      Original Author
      8 years ago

      Thanks for the input bargainhunter, I'm not overly put off by the door to the master bedroom leading off the living space but I do understand why some wouldn't like it. It's not conventional which might explain it, but might be a sacrifice I'll have to make.


      Thanks also baysig, this will be the home I retire into so looking at reducing energy bills is a driver here, will be fitting solar panels also. As for cover out the back I'm planning on pergolas covered by deciduous vines - would love to use wisteria, would look great so long as I keep it in check and it doesn't try to lift the roof off!

    • fianou
      8 years ago

      I like your new design, but I'd reverse it, with the living/kitchen area on the northeast side. Personal preference I guess... :) I like morning sun in the kitchen as I make breakfast and not streaming through my bedroom, but I like afternoon sun streaming through my bedroom if i have an afternoon nap.

      The redesign of the kitchen works well too! I like the idea of decidous vines for screening. wisteria are lovely, I also like clematis, they flower on the old wood, so cutting them back to control them they still produce beautiful flowers. Birch trees also provide fast growing dappled shade.


    • Brett Webster
      Original Author
      8 years ago

      Thanks fianou, I'm glad you like it given you were partially responsible for the changes! I've had a lot of positive feedback on this. As for kitchen location etc. I want the TV area on ten western side so I can watch it in the afternoons without to much glare. Eastern sun will be slightly limited by a couple of trees next door I. The morning so I don't envisage the master bedroom being flooded with light first thing - that said I usually beat the sun up anyway.

      Thanks for the tip on the clematis too, will look that up!

    • PRO
      Solarventi
      8 years ago

      Hi Brett, first off - well done for reaching out (without ego) and asking those that know and those that have tried and found results. If you are going with the brick veneer, the cavity is key to your moisture and thermal capabilities, after years within the house. Gyproc is not designed for anything but a 'skin'. If you increase thermal layer on the walls by asking he outer layer of the stud work with good quality silver sarking or Tyvek. Tape joints to eliminate vapour transfer to internal gyproc. Use 12.5mm gyproc on all external walls. OR Use 12.5 silver backed gyproc board on walls instead of previous. If coast effective -I would use this on the ceilings also. Principle being - isolate the internal breathing environment both thermally and other from the externals. Then deal with any ventilation or thermal issue by themselves internally. Look at why a house is designed, then go 100% better. The problem with roof voids is cold at night and heat in day, focus on high air barrier and high 'R' values here. Internally, consider + and -, as in, where it is cold-draw heat to it (South+ low) where it is hot, draw coolth to it (North & high). The result will be both continuos balance or equilibrium in comfort, thermally, energy and ventilation wise... Hope this helps : )

    • PRO
      Don Osborne & Associates
      8 years ago

      Hi Brett,
      In my opinion, you need to relocate the laundry and bathrooms to the south side of the house and get north aspect to 2 bedrooms with the larger living area between (as of 16 May). That way you will have less heating requirements all round.
      I would also advise to fill the timber frame cavity with good quality insulation and make sure to use an insulation sarking/blanket directly under the metal roof to minimise condesation as well as insulation between rafters/ceiling joists. Foil backed plasterboard is a bonus.
      You should also pay particular attention to how the different elements are constructed (when building) and ensure no gaps are left unsealed to maximise the efficiency of the solar design.
      For summer, you need to ensure natural breeze paths through the house to avoid mechanical ventilation and plan for ceiling fans for hot days without breeze.
      If it were me I would move the western window to the south wall and utilise the flow thru ventilation from the living area for summer.


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