Living in a strawbale house

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Notes from the Sustainable House Day  tour 2018

House design : Steve Hanson of Little Solar Houses

Builder: Alan Hauxwell, Yarragon. Completed 2013 ish.

Materials:

Floor- concrete slab on waffle pods and perimeter insulated with polystyrene panel.

Walls- strawbale with lime/ sand render. Mostly internal, rammed earth feature walls for added thermal mass are made from local road sand from Shady Creek just north of Yarragon. External timber cladding is with silvertop ash.

Windows- composite timber/ aluminium double glazed from Miglas in Melbourne. North shading is temporarily from shadecloth while the ornamental grape vines grow.

Ceiling insulation- sprayfoam sprayed under the roofing iron/ sisalation.

Roof- colorbond

Using the Energy Freedom Home headings:

Lighting

LED throughout except for 1-2 halogen bedside lamps remaining

Draught proofing

BBSN did not have our blower door at the time the house was built but testing since has shown a result of 5.3 ACH50, with the biggest leak identified in the sprayfoam insulation near one of the rammed earth wall ends. I assume it was hard for him to reach at the time. The woodheater has obligatory ventilation holes too.

Insulation

The strawbale walls have an R value of about 12, the windows about 0.5, the sprayfoam about 4. The small area of rammed earth wall exposed to the outside have a very low R value but heat transfer is slow as it is so thick.

Appliances and cooking

We became converts to induction cooktop cooking when we saw it at a friend’s house. It’s quick, responsive and easy to clean. Electric oven, microwave. Some preheating of the kettle with an old one on the woodheater. I try to minimise standby power use by turning things off at the wall. At least some thought went into power point placement to enable that.

Heating and cooling

There is no cooling device other than ceiling fans. The only heater is the woodheater. In the ceiling of the heater alcove there are ducts that run to each end of the house with in line fans- a heat shifter. Our daughter likes to use it for her end of the house but we hardly use it for ours.

Hot water

The storage tank is located in a special cupboard next to the woodheater so we can thermosiphon from the wetback to the tank through insulated copper pipes. There are also 40 evacuated tubes (Apricus) on the roof, with the hot water pumped when the sensors indicate the manifold is hotter than the tank. There is no electric or gas boosting. When we had 3 teenage daughters at home there were times we had to light the fire for hot water rather than room heating but that is now a rare event.

Energy monitoring and control

I bought a Watts Clever monitor a few years ago. It shows only what we are importing from the grid, not our solar generation or export. I like that the monitor is always there rather than having to log in on a phone or computer. I plan to arrange a monitor for the off grid system shortly.

Solar power

We had a 4.8kw system from the start with normal grid connection with a SMA inverter. This year we have used some second hand lead acid batteries from Hazelwood to build a hybrid off grid system, installed by Geoff Boadle from Sustainable Impact. An extra string of solar panels of 2.7kw was added to charge the batteries. There are 2 strings of 24 batteries, each being 2V 468ah, giving 48V and 22464ah of which only the top 30% or so is usable to preserve the battery life. If the batteries are low I can flick a switch to top up from the grid instead of starting a generator. The whole house is now connected to the battery system, except the induction cooktop and oven and the electric car charging point. Planned modifications include installing a switch to move one of the strings of panels to either grid connect or battery depending on the season and also a switch in the main switchboard to move the oven/ cooktop between grid or battery depending on the season.

What’s it like to live here?

During construction, even before lock up stage, the builders and contractors remarked how cool it was to work in over summer and one was amazed how hot the water was in winter, just from the evacuated tubes. We find the temperature remains within comfortable levels almost all the time but we are glad to light the fire in winter. Our energy bills have been $800 paid to power shop over the last 12 months. Although the gas line runs through the property, we are not connected. No water bills either.

powershop power usage McIntyre rd

The reduction over the years reflects children moving out more than anything else. The battery system became live in July this year so future graphs should be even lower. Our daily chart is quite spiky reflecting days when we have charged the electric car either overnight or at periods without much sun, which often happens. If we were paying for petrol for about 15,000km per year that would be 750 litres * say $1.40= $1050 so I think we are well ahead.

Powershop spiky power use

Although we are paying for electricity, we are exporting more than we import as shown below:

 

myhomeenergy power usemyhomeenergy poweruse2

What did it all cost?

These are approximate figures as we haven’t kept a strict eye on it all over time.

The house cost about $550,000 with the original grid connect solar system.

The off grid battery system cost another $15,000 but I got the secondhand batteries quite cheap at auction so an all new system this size would be considerably more.

I expect our electricity imports to drop dramatically now. Even if we eliminated any power purchases, the off grid system will still take many years to pay off financially. How much value do you put on having power when it goes out all around? That’s happened once since July for a period of 3-4 hours during the evening cooking time which we were easily able to adjust to by plugging in an old electric frying pan.

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5 things to do to prepare your home for summer.

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#1. Install adjustable blinds or awnings on your east and west facing windows to block out morning and afternoon sun.
#2. Install a fixed shading device over north facing windows to block summer sun hitting the glass.
#3. Plant deciduous plants around the house to block summer sun hitting windows and walls, but allowing warming winter sun to enter.
#4. Clean the dust and lichen off your solar panels- they’ll perform better and save you more.
#5. Remember to close the curtains and blinds during the day to reflect as much sun as possible and then open them and the windows up at night to vent out heat.
Passive solar design means orienting your home and its windows to take full advantage of warming winter sun and shading out hot summer sun. You can read all you need to know in the Your Home technical manual.

Electric vehicle expo report

Les Grosberg discusses the Tesla S with Peter Stansfield of Gippsland Solar

Over 50 people enjoyed a detailed briefing on the present and future of electric vehicles in Warragul recently.

Baw Baw Sustainability Network presented the evening at Warragul RSL and featured vehicles ranging from electric bicycles and motorcycles to the high end BMW and Tesla cars, with presentations from the Alternative Technology Association (ATA) and Gippsland Solar.

Electric vehicles presented a number of advantages with lower fuel costs, much lower maintenance, lower emissions of all sorts and smooth and quiet handling. In many cases electric vehicles now outperformed combustion powered vehicles. Battery life, cost and charging at home and on road had improved markedly in recent times, but different systems used in different vehicles remains a limitation for public charging stations.

Range had been improved with Tesla S achieving 370 – 500 Klms on one charge, depending on driving conditions and style.

Paul Paton from the ATA explained that he had ridden to the talk on his Vectrix motorcycle from Ringwood to Warragul and it would cost him about 90c. He added that the full range of vehicle types were now being produced in electric version, even trucks, which often use hydrogen fuel cells.

“With no gears, clutch, exhaust, or radiator and a brushless motor there is almost nothing to wear out,” he explained, “except maybe some bearings.”

“Range is over 250 klms and torque is nearly double the equivalent combustion engine bike” he said.

“Unlike combustion engine vehicles, electric vehicles have better range in city driving because almost no fuel is used when stationary” said Mr Paton.

Shane Clayton form Gippsland Solar outlined the details of their Tesla S which runs electric motors on front and rear axels giving four wheel drive without drive train limitations, resulting in a very sporty performance.

Sean Holden of Chili Cycles discusses his test ride with Cr Peter Costos

 

“It included hands free driving, which I must confess I find still a bit disturbing” he said. “It is our standard business car, and is used continually with no problems.”

“We decided to install a Tesla charging station at our Traralgon site, which can charge from empty to full in less than 45 minutes, while guests have a free coffee!” Mr Clayton said. The cost of the power was so low, especially as they have substantial solar panels on their site, that they have offered the service for free. Home charging on off peak rates would cost $15.

“We have found the ongoing cost to us is around $1 per year.”

“We have quite a few weekend tourists coming down to Traralgon to tour around,” Mr Clayton said.

Our future garages will include solar arrays, inverter, batteries and car charging facilities as standard Mr Clayton explained.

www.bbsn.org.au

 

10 Energy Habits for Daily Life

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Energy costs are rising and the industry is changing rapidly. One thing remains the same- the best way to reduce your bill is to use less electricity and gas. Here are 10 quick tips.

  1. Turn off the lights, the ceiling fan etc if you are leaving the room.
  2. Don’t leave TVs on when nobody is watching them.
  3. Turn off all those energy using appliances at the wall when not in use. If you want to know how much power they use on standby, borrow a powermate through your local library or get an In Home Display that will show your current power use.
  4. Use relaxed set points on your heating and cooling system. That means setting the thermostat at a point that makes the machine work less hard but still reach a comfortable temperature for you ie 25 or 26 deg in summer and 19-20deg in winter.
  5. Replace your shower head with a low flow version so you use less hot water and need to spend less on the energy to heat it. The newer showerheads are much better than the initial offerings so if you were put off them years ago it’s time to try again.
  6. Keep the flick mixer tap set to the cold position when washing hands so you don’t draw water from the hot side which isn’t going to heat up in the time you are there.
  7. Install some kind of adjustable external shading device on your east and west facing windows. Stopping hot summer sun entering the house makes an enormous difference as does allowing the warm winter sun in. North facing windows can have a fixed width eave or shade that will function well if designed correctly.
  8. Check the seals on your fridge and freezer and replace them if faulty. They should have no visible gap and hold a $5 note snugly all the way around.
  9. Replace your heating, cooling, hot water systems with efficient electric heat pump systems (for southern Victoria). Then kick the gas habit completely by replacing gas stoves with induction cooktops. They will save you energy and money with a reasonable pay back time (less than 5 yrs usually) and you no longer need to pay a second supply charge for the gas and you are protected from rising gas prices.
  10. Last but not least- seal up those gaps that are causing too much air leakage.

For a thorough home assessment contact us here.

 

From hovel to haven- retrofit case #2

burke st unit

This 1980ish 2 bedroom, brick veneer unit has undergone an energy makeover along the lines of a previous post on “energy freedom”. The previous tenant was spending $1300 a year on electricity and gas and it was terribly hot in summer and cold in winter.

Lights have been changed to LED except in the kitchen where there is a strip fluoro which has been retained, and some rooms that have compact fluoros.

A blower door test prior to any work showed a result of 18ACH50 (air changes per hour at 50 pascals) which is indicative that a lot of energy was being wasted through air leaks. To address this, fixed vents in the ceiling of the kitchen and laundry were removed and the holes repaired, caulking was done around the architraves and windows, draftstoppas were installed over the exhaust fans in the bathroom and kitchen, compression seals were fitted to the doors as well as bottom seals and the holes in the walls left over after the removal of gas heaters were filled with expanding foam. A repeat blower door test showed 9ACH50 – half what it was.

The unit is on a concrete slab so no floor insulation was possible. It is a brick veneer with one hardiplank wall in the garage- pictured above. Sprayfoam has been injected into the wall cavity through holes in the brickwork, or after removal of two boards in the garage.

sprayfoamsprayfoam brickwork

The holes are filled with mortar afterwards- seen in the middle of the picture above. The ceiling had existing fibreglass batts which are probably R2 but there were a few areas with no coverage at all. The gaps were filled then another layer of R3.5 earthwool roll was placed over the top, running perpendicular to the batts and covering the ceiling joists.

As mentioned before, an old gas wall furnace that was no longer in use was removed. It was just an eyesore as well as a source of air leaks. The newer gas heater was also removed, as were the gas hot water service that was aged and the gas cooktop and oven unit. With no gas appliances left, the meter was disconnected.

Efficient electric appliances have replaced all those gas ones- a Sanden heat pump HWS, new electric oven with induction cooktop and a the most efficient heat pump space heater/ cooler on the market- the Daikin US7.

The unit already had a solar PV system installed some years previously.

The windows are single glazed in cheap, non thermally broken, aluminium frames and are of the sliding type. In other words, they couldn’t be worse from an energy efficiency point of view. All but 3 windows have been improved with secondary glazing- acrylic sheet held in place with either magnetic strip for the smaller windows or with a timber bead for the larger ones. Three windows were left not done to allow easy cross ventilation. Bedroom and lounge windows had pelmets fitted, made with clear acrylic sheet, held in place with 2 bolts to the existing curtain railing.

 

The next tenant has moved in and should notice their energy bills are almost wiped out- but we’ll have to wait and see.

Below is a list of the costs involved:

Top up ceiling insulation (DIY labour) $1001

Sanden HWS (installed) $4162

Electrical work for new oven/ cooktop, HWS, wall insulation $1769

Weatherstripping materials (DIY labour) $161

Plumbing contractor (removing gas appliances, installing new toilet) $486

Secondary glazing (DIY labour) $1415

Daikin US7 (installed) $4150

Wall insulation $4631

LEDs and new fittings $187

Belling oven / cooktop $1800

Total cost $19,762

The benefits?

Saving on gas supply charges (annual) $291

Expected reduction in annual energy usage bills of $1000

Much greater comfort – priceless!

This Scorecard certificate shows the home now achieves a 10 star rating with a 6 star rating before the improvements were made. More info on the Scorecard tool is available Screen Shot 2018-01-28 at 2.42.41 PMhere. It reflects the expected costs in running a home after assessing the building shell and the fixed appliances used for heating, cooling and hot water. It does not consider the number or behaviour of occupants or other appliances.

 

Why we need to act fast on CO2 emissions.

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This is a chart showing the level of CO2 in the atmosphere over the last 800,000 years which spans all the time since humans have evolved. It is actually a short video which you can watch hereThe rate of rise in CO2 is showing no sign of slowing. Permafrost is melting which will add more and more methane, a potent greenhouse gas, to the atmosphere. Arctic ice cover is shrinking year on year. Greenland and Antarctic ice is steadily melting. Ocean acidity is rising. Weather patterns are changing and severe storms, bushfires and floods are more frequent. Corals are dying, sea grasses  are dying, habitat ranges are changing and biologists are stating we are in the midst of a huge extinction event.

It is not a pretty picture. How best to respond?