What do you think of this house?
Roof look a little unusual?
Well the roof, and the walls, are built using seeweed!
The seeweed provides a long lasting external surface, which as well as being a natural renewable resource, has great insulation values.
To find out more, with lots of pictures of a spectacular interior, see the www.dezeen.com website.
I have previously talked about Bushfire reserve supplies. . . . But how much?
I see various minimum water volumes put forward for bush fire reserves. For example in early 2014 the following applied.
Just because there is a minimum requirement that doesn’t mean that is going to be enough water to deal with an incident for your property. Here are some thoughts on what I feel is appropriate.
The above figures are indicative and any spray system should be properly designed.
Photo from Blazecontrol.com
If you read up about energy efficiency you will come across the expression ‘Thermal Mass’ . . . . . . but what is it? . . . . . and how does it work?
The most common materials with Thermal Mass in new houses are; Concrete, Stone, Slate, Tiles and Brick. In some cases water tanks can also be used to provide Thermal Mass. (But not easy to use as evaporation can reduce the effectiveness, and the resultant humidity can cause damp)
A key characteristic of these materials are they are dense(heavy) and have the ability to absorb excess heat and then release it in cooler periods.
Thermal Mass need to be exposed. Covering with carpets or timber floors insulates them and prevent it from being as effective.
The trick is to put either ‘Free or Low Cost Heat’ or ‘Spare Heat’ directly into the thermal mass which is released to keep your house warm longer.
Direct winter sunlight on a floor or a wall is a great source of free heat. Just make sure you have Properly Designed Shade to keep the summer sun out.
Sources of low cost heat are things like using off-peak power, or excess solar power. This can provide either direct heating, or run heat pumps circulating hot water into a slab.
Each time a wood heater is filled with wood it should initially be run with the vents fully open to minimise build up of creosote and soot in the flue . Without a thermally massive surround to help absorb the excess heat you can quickly over heat your room.
Any exposed thermal mass that is not heated may feel cool to the touch as it will be no warmer than the room temperature. However as the room cools this thermal mass will still release its heat back into the air to slow down the rate the room cools down. (This is known as ‘Thermal Lag’).
I frequently see comments like “Ceiling insulation is next to worthless in summer.”
I have even heard people say “With a hot roof space it will be overwhelmed.” and “After the sun has gone off it stops the house cooling down.”
Here is the truth:
The ‘Rainfall Intensity’ is important when thinking about things like; Roof Gutters, Down Pipes, Stormwater Pipes , Tank Overflows, and even how high your house is above ground level.
When talking about heavy rainfall you will frequently hear talk on the news about things like a ‘1 in a 100 year storm’. What that means is that a statistical calculation indicates that a storm of that strength is only expected to occur once in any 100 year period, the ‘Recurrence Interval’.
There are two rainfall intensities that the building codes normally consider. They are based on the peak 5 minutes during a storm for vaious ‘Recurrence Intervals’.
Intervals can be from: 1 in 20 years to: 1 in 100 years (See this link for more information: Roof Choices)
Statistical intensities have been calculated for all locations in Australia and are available at the Bureau of Meteorology (BOM) Website.
Search for ‘Intensity Frequency Duration (IFD)’
| Duration |
1EY 1 year |
50% 2 years |
20% 5 years |
10% 10 years |
5% 20 years |
2% 50 years |
1% 100 years |
| 5 mins |
44.9 |
60.1 |
83.4 |
99.7 |
121 |
153 |
179 |
The units are mm of rain in 5 mins (Multiply by 12 to get an hourly flow rate)
Parts of the Plumbing and Building Codes refer to areas of “Low Rainfall Intensity”.
A location of “Low Rainfall Intensity” means the 5 minute rainfall intensity for an average recurrence interval of 20 years is not more than 125 mm/hour.
Downsizing to a smaller new house for your retirement? Don’t forget to think about solar power.
Last week I revised a post ‘Solar Power is it Worth It?‘ but if you are approaching retirement, like me, there can be an even bigger financial advantage in having solar installed.
Because we are both out at work during the weeks I calculated that with a 1.5kw system costing around $3,000 panels we will save:
See the original post to see how I arrived at these figures
After retirement its likely that our weekday usage patterns will be more like the weekends so our annual savings are expected to be 365 x $1.40 = $511.
I am assuming that you will have some money from superannuation, but not enough to mean you won’t be eligible for a state pension.
If you have more assets then the Government limits your pension. It will be reduced by $39 per annum for every extra thousand dollars. (Basically the government takes the interest)
Invest $3,000 in a solar power system and that becomes part of your house, which is excluded from the governments asset test. You will therefore be eligible for an extra $117 a year pension.
The expected benefit for your $3,000 investment is:
$511 + $117 = $628.
20.9% Return with a Payback of Under 5 years
I don’t know about you but i’m hoping to live a lot longer than 5 years beyond retirement!
For more about solar panels see Sustainability, Solar Power
There is a lot of marketing information around about Grid Connected Solar Panels but not many independant facts. Here’s an example of an evaluation of a basic system for a house.
Weekdays (as we both work and the house is empty during the day) we should be able to put at least 2.5 kwhrs into the grid and use a maximum of 2.7kwhrs running fridges etc)
Income 2.5kwhr @ $0.08 = $0.24
Saving 2.7kwhr @ $0.3152 = $0.85
Benefit = ($0.24 + $0.85) x 260 days = $283
Weekends we probably will only put 1kwhr into the grid as we may well be at home using power for TVs, heating or cooling, etc.
Income 1kwhr @ $0.08 = $0.08
Saving 4.2kwhr @ $0.3152= $1.32
Benefit = ($0.08 + $1.32) x 104 days = $145
Total annual benefit is $428.4
Well there are some 1.5kw systems being advertised now with various rebates which cost less than $3000.
If you had $3000 on term deposit returning 4% that’s $120 a year, which would then be taxed. Alternatively if you put the cost on your mortgage that will mean that you are borrowing $3000 at a rate of around 6%. That’s costing around $180.
From these figures it looks like for the basic system you will be around $250-$310/year better off.
NB. I first did a Cost Review in 2011. Since then the cost of panels, and the government subsidies, have gone down. The cost of power from the grid has gone up. The overall financial advantage is around the same.
This is a fairly typical rainwater collection installation.
Gutters discharging to a pipe which discharges onto a screen fitted to the tank access point, cheap and cheerful!
I must have seen it hundreds of times . . . . . . but it has some negative implications on the water quality you will get from the tank!
Thanks to SaveH2O, of Supadiverta
This diagram indicates a charged rainwater collection system. These are sometimes called either a “wet” or a “pressure” system.
NB. This diagram has been simplified for clarity. A leaf diverter, and an adequate overflow, must also be fitted.
With this type of system a section of the pipework always remains full.
As the pipes are under pressure it is essential all the joints in above ground and underground pipework are fully watertight.
I have previously carried out a worked example of the insulation of a Brick Veneer Wall, so as a comparison here is double brick wall.
I have also shown (in brackets) the effect of using a hebel block in place of one of the brick ‘leaves’:
| Element |
R value |
| Outside surface air layer |
0.03 |
| 110mm brick |
0.08 |
| 25mm cavity |
0.12 |
| 110mm brick (*or 125mm Hebel Block) |
0.08 (*0.81) |
| Plasterboard 10mm |
0.08 |
| Inside surface air layer |
0.12 |
| Total R value |
0.51(*1.24) |
| U value = 1/R |
1.96 (*0.81) |
The heat losses or gains for 150 sq m (fairly typical external wall area) of this type of double brick wall at 15 degrees above, or below, outside temperature will be:
Area x ‘U’ x temperature difference = watts per hour
150m2 x 1.96 x 15degrees = 4410watts per hour
Heating/Cooling Requirement = 4.41kw/hour
Using Hebel for one of the leaves will improve the heat loss as follows:
150m2 x 0.81 x15degrees = 1822watts per hour
Heating/Cooling Requirement = 1.82kw/hour
Still not as good as the 1.17 kw/hour of the typical brick veneer construction
Don’t forget heat is also lost through windows, ceilings floors and ventilation.
