Footings, Slabs & Concrete

Notes for bulding codes , standards and compliance for low rise at CIT tafe in Canberra, ACT. (quiz 5 topic 7)

What are limitations of 3.2.1 and what do they mean?

this refers to fooings and slabs, and is limited to:

  • footings on soil of A,S,M,M-D,H,H-D
  • <30m long slabs
  • excluding construction joints
  • <2 trafficable floors and walls heights <8m
  • supports only a single concrete floor
  • has no wing walls
  • site is normal
  • site is not in an alpine area

 

List four things that are required when preparing footings

  1. excavation to be clean cut with vertical sides if possible
  2. slope of cut must be <1:40
  3. footing holes must be free of loose earth, tree roots & debris
  4. top soil with grass roots must be removed

 

What are the options for material going immediately under slabs?

Controlled or rolled fill of clay or sand must be used, followed by a >20mm layer of clean sand or graded stone termite management system.  The sand must have a blow count of <7 per 300mm.

How are stepped strip footing prepared and why do we have them?

When preparing the earthwork, the base must be horizontal or <1:10 gradient. The steps must be done in accordance as per table 3.2.2.2.  Mesh must overlap by 200mm.

It is so the masonry going on top of the strip footing doesn’t slide off.  To provide a flat surface to put the masonry on, and to ensure compression forces are transferred into the ground appropriately.

Why do we have a vapour barrier?

The vapour barrier protects the concrete slab from moisture.  It does this by preventing salts dissolved in groundwater from contacting the slab, and to stop moisture absorbing up through the slab.  3.2.2.6.

 

 

 

 

 

 

 

Advertisements

Thermal camera fun 

I like this one of the fridge, isn’t it interesting to see the refrigeration coil going up the side! 

Woops,  left this on! 

Hopefully some compost to come 

Who’s been lying on my couch? ‘

Great to see how a tree adds thermal mass and heat to a garden 

Should I get this checked out? 


I see you studs!  Also known as thermal bridges.. 

Building Codes, Standards & Compliance for Low Rise – Site preparation

What is the scope of part 3.0 of the BCA Volume two?

Part three lists the deemed to satisfy provisions that are considered acceptable forms of construction that must meet the legislative requirements for complying with the housing provisions (performance requirements)

For site works, what determines that a site is normal?

The soil classification (a,s,m,h,e), climate, trees (no large trees or major structures on site are removed) and ground water movement

What are the requirements when excavating next to a vacant property?

Excavation can be done provided that: (i) there are no buildings or structures on the adjoining allotment boundary adjacent to the excavation and, (ii) the excavation commences at the allotment boundary and is within the area defined as being suitable for excavation in Figure 3.1.1.1 and (iii) the slope of the unprotected embankment of the excavation complies with the appropriate soil classification slope as described in table 3.1.1.1

How must surface water be diverted away from residential buildings? 

For a slab on ground, the finished ground level external surfaces surrounding the slab must slope away at 25mm over the first 1m for low rainfall intensity, and 50mm in any other case.  Low rainfall is <125mm of rain in a 5 minute period with a 20 year period

What is the requirement for heights of the finished floor level (FFL) to be in relation to Finished Ground Level (FGL) for slab on ground construction?

Finished slab heights must be 100mm above the finished ground level in low rainfall area, 50mm above impermeable paved areas that slope away in accordance with above, or else 150mm in any other case.

What is the coverage required for stormwater drains?

The cover to 90mm class 6 UPVC stormwater drains installed underground must not be less than: (measured from the top of the pipe)

  1. under soil  -100mm or
  2. under paved or concrete areas – 50mm or
  3. under areas subject to light vehicle traffic –
    1. reinforced concrete – 75mm or
    2. paved – 75mm

For termite protection to what do the requirements of part 3.1.3 not apply?

If a building is in an area that is deemed not at risk of terminte attached, it does not require a termite management system or if it is made up of materials not subject to termite attach such as

  • steel & metals
  • concrete & masonry
  • fibre reinforced cement
  • termite resistant timber both naturally or preserved and treated.

What satisfies performance requirement P2.1 for termite management?

A termite management system is designed with the intent to deter termites from entering a building via a concealed route.  It will not stop termite activity from occurring on the site.

What are the requirements for termite protection for slab on ground (spray on chemicals are not to be used)?

The slab perimeter or external wall perimeter must have slab edge exposure (>75 mm), sheet material or granular material. (slab must comply with AS2870

The penetrations, control joints and area beneath the slab must have sheet material or granular material.

Can concrete slabs be considered part of a termite barrier?

Yes, a smooth non honeycombed exposed slab edge of at least 75mm can be as it allows for visible inspection of any termite attack.  Provided it compacted and cured to AS2870 (no air pocket, slowly cured)

Name three systems that can be used as termite barriers

Slab edge exposure for slab perimeter, termite shielding for some suspended floors, stainless steel mesh.  Termimesh, trithor, granulated material, ant capping

What are the requirements for termite barriers beneath suspended floors?

Capping over the piers, capping over the perimeter.  There must be a 450mm height crawl zone 2m in from the external wall, and 150mm high at the external edge.

What must a durable notice for termite barriers include?

  1. The system used
  2. the date installed
  3. where chemicals were used and its life expectancy
  4. advice regarding the scope and frequency of future inspections

 

 

 

 

 

 

 

 

 

Notes on the Building Codes, Standards and Compaince for Low Rise in Australia

These are my notes for the exams upcoming.

What is the national construction code?

A u niform set of technical provisions for the design and construction of buildings and other structures and plumbing and drainage in Australia.  It allows for climatic, geographical and geological conditions.

What is a performance Solution?

A performance solution (also known as an alternative solution) complies with a performance requirement as well as being greater than or equivalent to the deemed-to-satisfy provisions.

Why use an alternative solution?

It allows you to do something other than the DTS.

It may allow for more flexible, cost effective, simpler or more innovative way of achieving a performance requirement.

What is acceptable construction?

It is a nationally recognized way of doing things that meets the performance requirements.  They typically exist with manuals and in practice and are laid out in the BCA vol 2.

What is the difference between prescription regulation and performance based regulation?

Prescriptive tells you “how, what and when” with little remove to move.  Performance sets levels of “what and when”?

What is acceptable construction practice in volume 2 of the BCA?

A specific, known, understood and documented method laid out in the BCA volume two that explains how to meet a performance requirement.  IT is a nationally recognised way of doing this.

What parts of the BCA are mandatory?

Section two of Volume two and appendixes B to J of Volume 1.

Several of the performance requirements require something to be done “to the degree necessary” – what does this mean?

It means that the solution must incorporate all of the requirements that will be listed immediately below this statement.

How do I establish the scope and suitability of documentation that a certifying authority will need to assess my performance solution?

Ask the certifying authority.

Does one need a specialist practitioner to incorporate a performance solution?

No, if you know what is required and why it is required then you will be able to do it.

Can I incorporate a performance solution for either a small part of a design or the whole design?

Yes, a PS can meet either a performance requirement of a deemed to satisfy.

How to know if someone is an expert for when “expert judgement” is required?

If someone is recognized by their peers, industry bodies, certified authority

How does one determine which performance requirements will need to be addressed when developing a particular performance solution

There is a procedure that dictates what is relevant in volume 1 1.0.7

What can I do if I think the content of a mandatory performance requirement is too stringent for my particular building?

You must see the relevant authorities administrative provisions dictated in legislation.  Each state and territory have different rules for this.

Why don’t all performance requirements have quantified values that can provide a benchmark for assessing compliance for performance solutions?

Because some are qualified as opposed to quantified.  Qualified values are described, with words!

When a performance solution is being developed, how does one identify the issues that will need to be addressed in the proposal?

One must look in the BCA to identify which PR the PS is to apply to.  Then one must identify all the other PR that may be impacted or affected by the application of the PS.

Some PR will list what needs to be considered when meeting it.  If not, meet with experts, local authority or others who can advise.

How are performance solutions required to be assessed?’

There must be evidence to support the use of a material, product or form of construction meets the performance requirement or a deemed to satisfy. OR

Use a verification method as approved by the NCC or appropriate authority, Expert Judgement or comparison with the deemed-to-satisfy provisions.

See clause 1.0.5  – evidence of suitability issued by an appropriate regulatory authority.

Or use of approved software to analyse particular PR – such as truss software, or energy efficiency software.

Comparison with the deemed to satisfy provisions is an acceptable assessment method, what does this mean?

Deemed to satisfy is an accepted method.  Therefore if you can prove that you meet or exceed the DTS, your method will be suitable.

 

 

Types of classes of buildings in Australia

  1. (1a) a single dwelling that is a detached house, or more attached dwellings.
    1b – a boarding house or guest house not ontop of another building unless a private garage
  2. Apartments – 2 or more sole occupancy units each being a single dwelling
  3. Residential building for transient persons – hotel, model, school, detention centre
  4. A dwelling in classes 5,6,7,8,9 if alone
  5. an office building
  6. a shop
  7. 7a – car park
    7b – storage or wholesale sellers
  8. a lab or handcraft place
  9. 9a  – healthcare building
    9b – assembly building
    9c – aged care
  10. a non habitable building or structure
    10a – private garage carport or shed
    10b – a fence, antenna, retaining wall, swimming pool
    10c – private bushfire shelter

 

 

Canberra Concrete Slab Construction – Ground Coupled or Insulated?

When building a house with concrete slab, should it be insulated or coupled with the ground?

Short answer – ground coupled in useful in warmer climates, insulated slabs are better in colder climates.

Often there are two polarised opinions on whether to couple a slab with the earth.  Does it help or does it inhibit, and ultimately does it make it more energy efficient or more comfortable?

A slab that is coupled with the earth benefits from the relatively stable temperatures that will be dependant on climate.  In Canberra for example, the 3m below ground temperature is around 16 degrees Celcius year round.  A slab that is ground coupled is typically most beneficial in warmer climates, where the colder ground temperature reduces summer cooling loads.  In Sydney for example, where you want to be cooler more often than warmer, a colder ground coupled slab is advantageous.

Canberra is a heating climate, and thus it is beneficial to minimize heating loads in order to reduce energy consumption.  This means a slab must be fully insulated from the earth as the earth otherwise acts as an infinitely large thermal sink.  This sink wicks away any temperature above 16 degrees.

This is particularly relevant for slabs that have in slab heating, or slabs that are warmed by the sun in winter.  The higher the temperature differential the faster heat will transfer from one to another.  This results in increased losses for slabs that are uninsulated when trying to raise the temperature above 16 degrees Celcius.

References:

http://www.yourhome.gov.au/passive-design/passive-solar-heating

Jigsaw Housing

http://www.jigsawhousing.com.au/blog/jigsaw-share-some-solar-tips

Energy Management in Transport

What are the 3 main problems with PEM fuel Cells? 

Proton Exchange Membrane Fuel Cells (PEMFC) use the energy in hydrogen and oxygen to produce electricity, water vapour and heat.  This can be useful in all sorts of applications such as fueling a car or spaceship with energy.  Hydrogen is twice as energy dense as petrol but can be more difficult to contain and transfer, and requires infrastructure.

In a PEMFC hydrogen needs to first be generated and stored.  This takes energy which can and should be produced from renewable generators such as solar and wind. Petrol stations could possibly become solar farms with micro hydrogen generation for your car.  This is perhaps what Hyandai hopes for with the launch of their world first mass produced fuel cell vehicle.

PEMFC also require management of their latent heat and water management but a bigger threat to their use is possibly Elon Munsk, recently calling them “bullshit” and determined to dominate with his superior lithium Ion electric vehicles.  NASA however has an entire program dedicated to their use for low emission space travel.

2. What factors determine aerodynamic drag?

Aerodyanmic drag is the pressure and friction fluid drag forces that result from the requirement to push a solid body through a fluid flow.  This results in loss of energy on the solid body, and thus in car design it is important to reduce aerodynamic drag.

Drag is directly related to the relative perpendicular surface area as this represents how much fluid body is affected as the object passes through it.

As drag is related to atmospheric pressure,  altitude and local winds can affect the drag coefficient.  Drag accounts for 2.6% of the energy loss in a vehicle, therefore it can be useful to minimize the drag resistance.  The affect that aerodynamic drag has upon the efficiency of the vehicle also depends on the speed of travel.  The faster a vehicle travels, the higher the drag resistance so it is particularly important in high speed applications such as rockets, planes and high speed trains.

3. List and discuss 5 drawbacks of electric vehicles.

Electric Vehicles (EVs) are slow.  EVs cant go far.  EVs are expensive.  EVs are dangerous.  There is no where to charge them.  These are five claims against the current electric car.

High performance modern electric cars, such as the Tesla S operating at high voltages than electric vehicles in the past, can out perform sports cars. The Tesla S has a motor in each wheel, providing better performance as each wheel can be given precisely the correct amount of power to maximize tracking and performance.

Range has only increased since the widespread adoption of lithium ion battery technology.  Ranges of 400-500km are achieveable today.  Whilst not everyone may have $100,000 for a new Telsa, the Nissan leaf at under $40,000 makes it an affordable alternative to a wide number of other combustion verhicles.  These prices will only continue to decrease.

Some people say storing hydrogen is dangerous. Surely this is no more dangerous than the current method of harnessing the power of over 2,000 explosions every minute in a piston engine.  That sounds inherently dangerous.

Charging stations could be everywhere, considering that every power socket can be a potential charging station.  The key is how to develop the charging relationship infrastructure that ensures trouble free use by the consumer.

4. One way to improve vehicle efficiency is to reduce weight by using composite materials. Discuss how this affects the crashworthiness of a vehicle. 

Crashworthiness in a vehicle is defined as the ability of the vehicle to minimize trauma and harm inflicted upon the occupant within a vehicle in an accident.  Current vehicles contain a lot of steel and other metals, making them heavy which provides them with a lot of force in accidents when at speed.  Steele however fails and damages in a well understood way, and hence smart design can make them much safer, consider the use of roll cases for example.

Composites tend to be stiffer and lighter.  So it is important to design them so that when in an accident, impact trauma is minimized to the user.  This can be done by designing particular parts of the composite to bend and absorp impact over time to minimize harm.

There is less known about composite materials, and this has stifled their widespread adoption.  Airlines however have gone from an aluminium focus have switched to a composite centred design.  Considering the high use of composite materials in F1 racing, it is perhaps quite likely that we will find more composites in vehicles to come. 

Tutorial 4

1 – Using 20c/kWh calculate:

a – Ten 100W bulbs used 6 hours per day.

Daily consumption = 100W x 6h = 600Wh
Monthly consumption = 600Wh x 30 days = 18kWh
Monthly Cost = 18kWh x 20c/kWh = $3.60

b – Colour TV set for 5hrs per day.

Colour TV uses approximately 100W.  Therefore,
100W x 5h = 500Wh /day
Per month = 500Wh x 30 = 15kWh

15kWh x 20 cents = $3.00

c – Night light of 1W left on continously.
1W x 24hrs x 30 days =  720Wh
720Wh = 0.72kWh
0.72 x 0.2 = 14.4 cents

2 – Benefits of Energy efficient lighting

Energy efficient lighting is a significant use of energy in the industrial sector.  Industrial use of lighting may account for 5-10% of energy costs, as for commercial space lighting can be up to 40% of total energy consumption.  It is therefore paramount to have an efficient and effect lighting system.

The installation of energy efficient lighting has multiple benefits a beyond the immediate saving provided by using a lower wattage light.   The lower consumption of power by newer lighting systems reducing the air conditioning load required to cool the space.  This cost can be significant.  The use of improved lighting and new technology means that morale and mood can be affected from total light, and colour temperature.

3. Problem

The facility Manager want to replace 34 W F40T12 lamps with 10 W LED lamps in 200 4-lamp fixtures which are operated for 3128 hours /year in an air conditioned facility. Assume F40T12 34-watt costs $2 each and lasts 20,000 h, while 10 W LED costs $12 each and lasts about 30000 h. Electric energy cost is $ 0.3 per kWh. The demand charge is $6 per KVA/month. Air-conditioner runs one third of the lamp annual operating time. The EER (Energy Efficiency ratio) of the air conditioner is 3. EER in this context is the ratio of cooling output (kW) to the electric power input to the air conditioner (kW).

Calculate

a ) the annual cooling energy saving on the air-conditioner load (in kWh)

b) the overall annual electricity energy saving, which can be achieved (in kWh)

c) the payback period of this energy saving opportunity investment (10 marks)

Information:
All the light energy of both lamps will be converted into heat energy and instantly added to the cooling load.
Power factor of the all equipment is one
AC runs for 12 months for purpose of cooling.
The lights operate for 12 months but do not operate continuously for 24hrs/Day.
The overhead costs, such labour cost for replacement is not included. Assume any replacement cost per each fixture.
The BF (Ballast factor) for both Florescent and LED bulbs equal 1.25.

200, 4 lamps fixtures, 800 Lamps total used 3128 h/pa,
Existing Lamp – 34W, 20,000h, $2
LED Lamp – 10W, 30,000h, $12
Electricity – $0.3/kWh, $6/kVA/Month
AC time = 1/3 Lighting tIme = 1042.6 h/pa

a) Find the annual cooling saving.

Ballast Factors are identical and therefore ignored in this case
First find the net energy saving.
Current System Consumption per year = 800 x 0.034 x 3128 = 85,081kWh/pa
New System Consumption per year = 800 x 0.01 x 3128 = 25,024kWh

The AC system uses 1kWh for every 3kWh of cooling provided, and runs one third of the time of the lighting
Therefore to the saving in annual cooling is (85081 – 25024) / 3 / 3 =  6673 kWh/pa
At 30 cents a kWh this represents $2001.90 of saving

b) Find the overall energy saving.

This is found by summing the lighting saving as well as the air conditioning saving.
Total Annual energy saving = (85081 – 25024) + 6673 = 60057 + 6673 = 66730 kWh
At 30 cents a kWh this represents a saving of $20,019

c) Find the payback period

Cost of implementation = $12 * 800 = 9,600
Energy Savings = demand reduction costs and energy saving costs
Demand reduction costs = 800 * (0.034 – 10) * 6 = $115.2 per month, is $1382.40 per year
Consumption savings = 113,441 x $0.3 = $34,032.30 p.a.
Total savings = $35,414.70
The simple payback period is = 9,600 / 35414.70 = 0.27107 years or 3.25 months.

4. What is coeeneration and how can energy recovery be used to improve efficiency.

Traditional energy generation is inefficient due to the high amount of thermal losses suffered to the system by heat rejection (think radiator on a car, cooling lakes for power plants).  Cogeneration and trigeneration captures that ‘waste’ heat and uses it for heating water or another fluid, to provide heating for hot water systems or air conditioning.  In a trigeneraiton system an absorption chiller is also used (which acts like a fridge in reverse) that allows coolth to be produced as well as heat and electricity.  The absorption chiller produces cold water that can be used for air conditioning.

Due to the usual waste heat generated from turbines, cogeneration is able to increase the efficiently of a system significantly.  A usual 40% efficient system can be improved to 80 or 90+% efficiency by use of capturing waste heat.  Energy recovery allows for (typically) thermal energy to be captured and used in any system.  The captured energy does not need to be for hot water, it may provide thermal heat to improve heat pumps or work in a chiller cycle, providing air conditioning for a building.

Other methods of energy recovery include the use of thermal insulation, which protects a surface from emitting or receiving heat energy, or material matrix energy capture systems whereby a ‘core’ is heating and cooled with a fluid such as air or water.

5. What are heat pumps? What makes them an efficient method of air conditioning? Should they be used in humid climates such as Singapore?

A heat pump works a bit like a fridge in reverse except instead of capturing coolth and rejecting heat, the reverse is used.  By using a refrigerant and a compressor, a closed refrigeration system can be used whereby a gas is compressed and heated up.  The heated gas goes through a heat exchanger to pass the heat to the medium such as hot water.  Once passing through this the gas is allowed to expand, cooling it further, to a much colder temperature than the ambient air.  The refrigerant is then able to ‘capture’ heat from the ambient air to warm up, allowing the system to recharge and be able to go through the cycle again.

By use this way the system can be used to heat or cool something with additional ‘free’ energy being provided by ambient temperature.   This can allow heat pumps to have very high efficiencies.  For example a hot water system can get 4kWh of energy for every 1kW of electrical power.

Heat pumps are particularly useful in humid climates for two reasons.  One is that it is typically warm, therefore providing higher efficiency for the pumps, as well a heat pump cycle can act as a dehumidifier, providing additional ‘coolth’ if required.