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Solar passive house: How to choose appliances


#1

Over the last few years we’ve been working with a designer on a layout for our new solar passive house on a difficult 4-5m fall south facing block in Picton, NSW.

We are now at the stage of getting tenders and needing to choose appliances and products for the home.

Who do I turn to to figure out what would be best for our home? Do we go all electric appliances with a solar setup, or part electric part gas, gas or electric water heating, best pool heating, which lights eg. Sealed downlights or flush mount or does it really matter in the greater scheme of things?

We follow Choice reviews and always buy recommend products but who can tell me which combination of products would be most efficient in my new home?


#2

The approach that is most intellectually appealing to me, especially since you have a greenfields opportunity, is a suitably sized solar array with batteries sufficient to ideally last days if necessary, and electric everything. If you have sufficient roof area solar hot water and pool heating would make sense to possibly lessen battery capacity required.

Re lighting, if you are running everything from your own solar power it comes down to aesthetics and personal preferences, noting anything LED is going to have less electrical load than anything with conventional filaments.

Simplistically, if you install a solar system with batteries that can sustain (eg) a 20KW load, you can ‘do what you want’ with that electrical load. Balancing ‘what you want’ against the costs of an appropriately sized solar system, and whether you stay on (and getting FiTs) or going off grid are economic (and sometimes practical) matters. If you use gas that will be a discrete cost for supply and use, while electrics will be ‘free’ or minimised.

I hope my rambling made sense. To get an overview of what is on the market you could visit the Enter Shop or G-Store here in Melbourne area.


#3

In addittion to the excellent advice by @TheBBG, get the best inverter you can, don’t go for cheaper Chinese brand ones as from information on some threads on this forum they don’t appear to last as long. Best here means well made by a company that is reputable, will be and has been long lived (many seem to appear then fold), has great support, has good warranty terms backed up by that previous long lived part, the product/s has/have very good reviews not just here but on specialist solar sites.

If you go all electric you don’t have to maintain two energy systems making it a single support person/business in the event of issues.

As for energy efficiency you can compare what each item uses (the energy efficiency stars which also give an amount of energy consumed for a known period) and then determine which will draw the least amount of power and will suit your size/capacity requirements. The energy stars aren’t a perfect answer but they are a good point at which to start.


Cool PV - combined solar panels and pool heating
#4

@grahroll and @TheBBG have already given good advice especially with solar HWS & pool heating, solar and battery systems, quality of systems etc. LED globes are the way to go, however when it comes to cooking get a gas oven/stove/cooktop if you prefer this as we do. We do have a solar passive house (built in 1994), wind power (1994), solar power and a huge rainwater tank (1999). Our basic idea was to be environmentally friendly without being restricted in the way we live. Another consideration for you may be the resale value of the property if you possibly get to sell it one day. This means having mains power and public water backup. Normally a passive solar house should fetch more resale value but then there could be buyers that like the house but not the challenges of alternative power systems etc. Keep going and good luck:)


#5

Great advice already from others. I’d definitely go all electric. No need to be paying for a gas service that would cost more in service fees than actual gas usage. The latest induction stove tops are very efficient and super quick to boil things. Probably just not quite as user friendly as gas though- gas flame is always easy to see just how much flame is hitting your pot. Induction stove top is much easier to clean compared to gas as it is just a single flat surface.
I’d go all LED lights as they are so efficient and these days you have a great choice.
Good luck.


#6

While I strongly support the use of LED lighting, be careful about the selection of downlights. If you are truly looking at the full solar passive, energy efficient house one of the factors is the prevention of leakage air. While all lights will cause leakage (you have to make a hole in the ceiling to get the wire through), downlights are particularly ‘leaky’. Also, there are regulations limiting how close the insulation can get to the downlight.
However, there are a number of downlights that are specifically designed to be covered with insulation and located next to construction elements - they have an ‘IC’ rating. Others also are specifically designed for solar passive houses, restricting air transfer - they have an 'IC-4" rating.
These ratings are not always obvious but should be on the box. Check with your lighting supplier to make sure they provide the right fittings!

Also, make sure you insulation installer knows that there is no restriction for installing insulation over the downlights. Don’t waste energy because there are gaps in the insulation. In fact, the insulation actually helps with restricting air transfer!

One additional consideration: In a truly solar passive house the air transfer from inside to outside is tiny, nothing like a ‘normal’ Australian house which leaks massive amount. This means that you will not get any fresh air into the house and there is no source of air to make up for any exhaust fan, like range hood or bathroom exhaust. Failure to provide fresh air can make the air in the house very stale, and opening a window or door just defeats the whole passive house process! So, consider installing a heat exchanger, which will heat or cool air coming into the house using the exhausted air!!

Finally, while gas has cooking benefits I would go for an all electric house. Having solar PV panels plus batteries could make you virtually self sufficient. Some of the electrical cost can be recovered by exporting excess power. Gas has two problems, the cost to have it connected is more than the usage - and cannot be recovered, Also, it will burn up oxygen making your house even more stuffy - remember the air changes in the house are very low!


#7

Having a passive house design does not necessarily imply a sealed air tight house. It is how Grand Designs presents and the UK rates a passive house. Is Australia different?

Is it more about being able to control heat transfer?And as suggested previously using heat exchanges the necessary air changes for a healthy living space?

My rattling memory suggests there are minimum requirements for fresh air exchange in our building codes (commercial and multi unit developments). Free standing residential buildings may not have a rigid requirement given you have opening windows in at least one wall of every room. There are however explicit requirements for bathrooms and the WC.

Depending on your objectives, it may be appropriate to consider gas for oven, cook top and hot water. Are you low impact or zero impact? Is your budget unrestricted? Will you keep your grid mains connection for backup?

It may be worth noting Bottled gas is remarkably cheap compared to reticulated gas in SE Qld. $300pa for two of us with instantaneous HW plus oven and cook top! In Bris Vegas with natural gas and a similar set up the gas bill was more than $800pa. The trade off is in the relative upfront costs. IE having the extra PV capacity and if off grid, batteries.

When the sun does not shine solar PV production is limited as well as any output of a solar HW panel.

It’s interesting to read that passive designs can be created to suit the humid sub-tropics.


#8

Thanks so much for the LED downlights information. I knew the basics about air leakage through downlights and had considered a ceiling mount light instead. It was an area when trying to research online I had trouble finding information for.

Our solar passive house is being designed to Australian codes and airtight ess is not one of those. If is was building in NZ that would be a priority.

As we have a south facing slope with a brick base wall under the main level are may use that as an opportunity to install a sub-floor roof ventilation system for extra cooling in the hot summer months.


#9

I wish I had an unrestricted budget! We will go with the essentials to begin with like good orientation and house layout, insulation and cross ventilation but allow provisions to add items on at a later stage. PV to start with room for battery later once technology advances or cost decreases.

I’m looking into grey water use on gardens and lawn and making provisions for that to install as a diy after the build.

I want to gather a bit more info on at home bio-gas production and whether that’s a future feasible option. Maybe I can start with bottles if it’s available here and look to make my own in the long run?

I’m also interested in wind power as our local council is a partner of the Macarathur Centre for Sustainability and seem keen to allow residential wind power generation.


#10

I’m very grateful for all this advice.

I currently have electric here for all cooking, cooling and water heating so not having gas doesn’t bother me. I would like to be able to have it in the future if at home bi-gas becomes a bit more main stream.

We’re looking to be environmentally conscious without too many restrictions. We have a small custom made parts business so the shed will draw a far amount of power but if I can lighten my footprint a bit I’m more than happy too.

Every little change for the better I can make, I will make. Most people think I’m crazy building what we are now and it’s just a weatherboard looking home with good orientation and layout!


#11

Just between you and me :slight_smile: I think downlights are a bad idea that should never have been allowed.

However downlights and LEDs are two independent factors.

While I too would strongly support the use of LED lighting, dimmable LED globes are still relatively expensive.


#12

Hot water is a tricky question. If your climate is such that you can do 90% of the job with solar hot water then how you boost it may not matter so much. However for most people that isn’t the case and PV electricity, particularly via battery, is an inefficient way of getting hot water. Instantaneous gas boost may be preferable. (The actual gas heater unit will be outside, so it doesn’t matter that it is consuming oxygen, and won’t make your air stale.)

So that decision could come down to your choice of ideological purity v. efficiency. (Even though the electricity is notionally free, in reality there was a high initial cost and so inefficiency does cost you money.)

Another question is the placement of the hot water tank i.e. split system v. integrated - which probably comes down to climate.

Finally, it is worth considering that an “all electric” arrangement has a single point of failure. If some part of the system is being serviced or has failed then you’ve got nothing.


#13

I’m not sure what style of LED downlights are being discussed. Our kitchen and main living areas are all LED downlights for regular lighting. The lights come as a single housing with the LED built into the housing. Once they are clipped into the ceiling there is zero air gap and zero leakage. The disadvantage is at end of life the whole unit needs to be replaced.

The first stage of our upgrade 2015 used LG branded lights. They dim wonderfully off a solid state dimmer. Four on one circuit.

The second stage for three rooms 2016 we were able to obtain a similar fully enclosed and sealed downlight fitting with a CE rating. These were supplied from L&H. They were also designed for dimming using an electronic dimmer.

So there may be solutions to suit your needs and enable you to use LED down lights while maintaining the integrity of the ceiling insulation? They are now one third the price of what we had to pay!

Just an example


#14

Ditto (for LED globes generally).

Whether to use downlights is an aesthetic choice, regardless of globe technology. This industrial vibe is all the go these days. :slight_smile: Not my cup of tea.


#15

We have an older house, and use them as a discrete way to add light as needed. It’s also a long way to the ceiling? We have feature dangling light/s and lamps in each room that serve as the main lights. Also all LED.

P.s.
Our style sense isn’t driven by the vintage of the house. Technically it should be lit with whale oil lamps and candles, given it’s age and history. There’s just a lack of authentic 19th century electrical lamps these days. Perhaps carbon arc lamps which were all the rage for a modern street light from the 1870’s?

LED lighting offers much more to realising unique or retro designs?


#16

Hi ‘Person’
There has been a radical change in the construction of downlights. The old halogen downlights, usually gimbal type, were truly dangerous and they also leaked massive amounts of air. The massive restrictions in their use because of the fire hazard not only to insulation but also to the construction of the house. This was all because of the massive heat from the halogen lamp.
However, the new LED downlights are completely different. Not only do they use far less power , they operate at far lower temperature. This means the downlight can be constructed to allow it the be fully covered by insulation (IC), some can actually be in contact with wood structure (IC-4).

Also, dimming is possible for many LED lamps and it does not add a lot to the cost to the fitting. Generally downlights are far less expensive than surface lights - it is possible to get a downlight for the same price, possibly less than a very basic ceiling light.
As for dimming, the dimmer is the biggest cost, they are all very expensive - do not buy a cheap one to save money as they will not work!

The best place to check out lights is on-line. If they do not list the insulation rating then email the site. They generally state whether a downlight is dimmable.


#17

We built a new house last year and I found the yourhome.gov.au website fantastic. They have a page devoted to appliances which might give you some ideas: http://yourhome.gov.au/energy/appliances

We made the choice to go all electric with our appliances. I didn’t want to have to pay a daily charge for both electricity and gas. The evacuated tubes for solar hot water means we get our water heated at no cost at least 3 months of the year (in Melbourne). I also love the responsiveness of the induction stove. Our LED downlights are similar to those mentioned earlier where the insulation can go right over the top (I would support the comment about ensuring your installer knows that!)

We’re a family of 4 with a 5kW PV system and we have paid a total of about $100 for energy over the last six months (on the standard feed in tariff).

All the best with your build!


#18

I’ve been through this process myself in WA, about 1km from the coast. I found that the house design and the characteristics of specific location, should be your main concern.
In my case being close to the coast meant that in the summer season, there was a predictable cooling sea-breeze most afternoons, but without internal and external temp sensors it was all to easy to think that the windy exterior was cooler than indoors, ie, thus opening the windows too soon to cool the interior, likewise the roof vents. So good sensors and possible some automated window opening devices might be worthwhile.
also in my location, the fridge was the heaviest user of power, ie, over a year more than heating and cooling, you too will need considerably less of the latter than conventional homes.
My experience was that cooling my home was easier than keeping it warm in the cooler months. So, I would recommend increasing exposure to the spring and autumn sun, ie, reducing the depth of your roof overhang; increasing the window openings breadth, ie, the return for curtains is seldom as large as architects imagine. Lined curtains with pelmets, roman blinds with 100mm+ wider than the frame are also good maybe with added velcro patches to hold them in place.
Double glazing makes sense, but using the glass type that permits solar entry, some types do the opposite!
Room positioning is critical you really need to put living spaces on the north and sleeping on the south and east, ie, morning sun in a bedroom is lovely, and not overly hot. Bedrooms and offices typically need desks, beds, chest of drawers, filing cabinets, so are also probably better on the south, with windowsills 800mm+ above ground. Dark tiling on concrete mass really makes for a wonderful source of draft free heating, warm feet and a cool head - heavenly!
Some years ago I asked Choice what they would recommend for kitchen appliances, Induction worktop, Convection Microwave and a non electric pressure cooker, no oven, no dishwasher.
Why do you want a swimming pool? Are you a keen swimmer, ie, all year round for exercise, then a tiny one with a pump for a current to swim against. Could be a heat sink, ie, thermal mass.

I mention these designs, because, what you need in appliances depends on how your house performs, what you need in your lifestyle and your location. How much heating are you going to get from the sun, and how much cooling from a suitable breeze, could mean no need for air-con or additional heating, ie, none at all! Hence how significant is power production? Do you eat out, or all meals at home and lots of entertaining - cooking is essential, etc.


#19

Just a couple of things to add to the great discussion here. We custom-built passive-solar and love it, and chose no gas not only to avoid the extra fees associated with its supply regardless of use level, but for environmental and health reasons - gas being a fossil fuel and also toxic within the home. We chose an induction cooktop and two things I found were that it gets very hot underneath so having a cupboard for storage of things like pots and pans is wise, rather than drawers, and I regret having only 3 rings and wish I’d gotten a bigger one with more, as the ring size needs to match the pot size.

We chose solar hot water which does a great job, but I do wonder whether it would have been better to use that roof surface for more PV panels as a lot of the time the water doesn’t need more heating as we don’t use a great deal. It may have been better to have PV panels and an electric storage heater, so that their energy can go elsewhere when not needed to heat water. It would be great if someone made a solar hot water system that allowed for this - I’m not aware of any that do though.


#20

A heat pump is a great alternative.

We replaced the 400 litre electric HWS at our previous residence with a 400 litre Saxon heat pump, and it used 80% less electricity and cost 70% less to run.

Our current home already had a 315 litre Conergy solar HWS installed and it works well.