ACV de Edificação – Mais fácil e perto de você (Portuguese)

Quantificar sustentabilidade ambiental foi o desafio que deu origem à empresa eTool. Desde 2010, os amigos e engenheiros australianos Richard e Alex desenvolvem o software eToolLCD para realizar cálculo de impacto ambiental na construção e promovem uso da metodologia Avaliação de Ciclo de Vida (ACV) para garantir performance ambiental genuína nos projetos em que participam.

Desde então, a equipe da eTool cresceu e expandiu da Austrália para a Europa e agora também para as Américas. A empresa já completou mais de 200 análises de projetos residenciais, comerciais e de infraestrutura, prestando serviço de consultoria ou fornecendo solução de software para a equipe de projeto.

O software eToolLCD é totalmente web-based, atende às normas ISO 14044 e EN15978 (específica para ACV de edificação), possui atualmente mais de 1.500 usuários ao redor do mundo e pode ser utilizado para obter pontos na certificação Green Star, BREEAM, LEED, entre outras.

Eu trabalho com a eTool desde 2012, onde me especializei em Avaliação de Ciclo de Vida e fui líder da equipe responsável por conduzir os estudos técnicos e colaborar com a equipe de desenvolvimento de software. Depois de morar cinco anos na Austrália, voltei para o Brasil para dar continuidade ao trabalho que iniciei em 2014, mas agora em definitivo para desenvolver a eTool Américas. É um grande desafio e também uma realização pessoal e profissional trazer para o Brasil uma metodologia que ainda não é muito utilizada, mas tem um grande potencial para auxiliar equipes de projeto a reduzir o impacto ambiental das construções e também demonstrar viabilidade financeira por meio da Análise de Custo do Ciclo de Vida.

Somos uma empresa apaixonada em projetar melhor e garantir bem estar social e harmonia com o meio ambiente. Estou entusiasmado para trabalharmos juntos.

5 Ways to add value to your services using Life Cycle Design

Life Cycle Design (LCD) has quickly become the go-to method for defining sustainability in buildings in governments, green building councils and organisations around the world. It is considered best practice for good building design by the International Standard Organization (ISO 14044) and is a powerful methodology for ensuring genuinely sustainable and high performance outcomes.

This article and video recording provide an overview of Life Cycle Design and explain five ways to add value to your services using LCD. Be inspired by how LCD has been incorporated in different sectors and projects, and how key stakeholders have taken it on board.

Some of the topics covered include:

What is Life Cycle Design and the methodology
The importance of green buildings and measuring building environmental performance
Green Star projects – general overview
LCA as a required part of ESD tender documentation
ISCA and use of LCD as an integrated desgin approach
LCD for regulatory approvals
Marketing and sales campaign
eToolLCD software 




Car Park Lighting Sensors

So if you’re designing an apartment building and you’re stuck with an underground car park things can get pretty nasty with energy consumption.  With no natural light and a clear safety requirement to keep the area lit all things point to an energy hungry lighting solution.   Even the most efficient lamps will still burn a lot of power running 24 hours a day, 365 days a year.

The most obvious solution to drop run time is lighting controls.  Specifically motion sensors.  But how should these be set up, and how does the set up (number of lamps per sensor and lamp shutoff delay) actually effect the energy savings the controls will achieve?  The short answer is, make sure they turn off really quickly after the car or person is out of the area.  The long answer is below:

It’s Complex…

The interplay between the car park layout, vehicle traffic, pedestrian traffic, simultaneous use of certain areas of the car park, probability of a specific car bay being accessed, the shut-off delay timing and the distribution of sensors means calculating light run time is very complex.  Pondering the possibilities got the better of me and I ended up running a simulation to determine effect of some key parameters.

A Conceptual Car Park

The conceptual car park looked like the below pick.  Effectively 150 bays with one pedestrian access and a main vehicle exit point at one end.

Car Park Map

I used some basic lighting design to work out how many lights would be needed (single globe T5s) to achieve an adequate light levels (50lx).  The calcs indicated a requirement of about 80 lamps.  I just placed these in the road ways and walk ways in my conceptual design.  These are the numbers with the x in front of them.  In reality they’d be probably be spaced more evenly but this satisfies the requirements of the model which is just to see how many lights would be triggered when each bay was accessed.

Which Car Bay Triggers which Lamp?

That was a manual process of thinking about how a person will walk from the lift to the car, and then how they will drive out (or vice versa).  The below diagram shows that if car bay 125 is accessed the blue line will be traversed by the car driver and passengers, whilst the red line will be travelled by the car.  All the lamps highlighted in red will subsequently need to fire.

Car Park Map - Lights Triggered By Bay 125


I got some stats on how many trips and average household does from here and here.  The Sydney data also gave these neat graphs on when the trips occur as well.  This enabled me to put a probability on a given car being accessed at a certain time of the day.  The sensors are obviously going to give the most benefit during lower trip frequency times.  But depending on the set up, you can even get a reduced run time during the peak times in this car park (not every day, but some days there’ll be savings due to the random nature of when people take a car trip).

Screen Shot 2015-05-24 at 2.59.53 pm

After some sense checking I ran the simulation for different combinations of motion sensor parameters.  The focus was on:

  • The delay before the lamp is shut down after the motion sensor is activated (or re-activated)
  • The number of lamps per sensor (if you whole car park is wired to one sensor, you’re not going to get as much benefit)

The below chart shows the results.  It looks pretty clear that the most important attribute is the delay before the lights are shut down again.  Amazingly, with 10 lamps per sensor a 90% run time reduction could be achieved if the lamps only fired for a minute.  10 lamps per sensor is probably as sparsely as you’d want to space the sensors to make sure they fired when there was movement

Simulated Car Park Lighting Energy with Sensors

Pit Falls

The simulation is obviously not a real live thing so I want to note some possible pit falls.

  • I got lazy and didn’t model weekend days separately.  So the actual savings are probably greater than what I’ve reported above.
  • If you car park is full or big rodents that trigger motion sensors 24 hours a day, the savings won’t be achieved.
  • My “Shut off delay time (mins)” is actually the lamp run time from when the motion sensor is first fired during a particular event, not from when it was last fired during that event.  So for you to achieve the 1 minute shut-off delay, you’ll probably want the light to go down 5 or 10 seconds after there was no motion in an area.  Perhaps this would cancel out the additional savings you’d get from lower weekend trips.

Other Car Park Lighting Ideas

Although motion sensors in car parks are an absolute no-brainer, there are also other things that can be done to make car park lighting smarter, a few of which I’ll include below.

Lux sensors may also be utilised with dimmable lamps to ensure light levels over the requirements are not delivered and hence energy savings may be achieved due to lower average lamp power.  The benefit of lux sensors in underground car parks is limited however due to a lack of natural light.

A better coefficient of utilisation can be achieved with light coloured rooms (more reflectance, so better light utilisation from your lamps which means you’ll need less lamps).

The lamp itself should be considered carefully and in conjunction with the lighting controls.  The most efficient globe in the world may be the wrong choice if you need more of them than necessary.  Similarly, if it won’t handle being turned on and off all the time, that’s going to be a problem.

The light housing can also help if it’s got a nice reflective backing to disperse the light where it’s needed (down and sideways) instead of where it’s not (up).

Brown Paper Background

eTool International Residential Benchmark (Methodology Summary)

Below is a summary of our approach to the International residential benchmark.  A full EN15978 report on the benchmark model can be found here.  International Residential Benchmark Weighted x10 dwellings v28

In light of eTool’s recent exploration into global markets, we thought it prudent to create a “global” benchmark for housing developments.  eTool will be using this benchmark for all future housing projects. The reasons an international statistically mixed use benchmark is the most robust model to compare designs against are as follows:

  • The planet does not care what kind of house you build only how close it is to zero carbon. A mixed use benchmark provides a fair comparison of performance across different house types be it apartments, detached, maisonettes etc.
  • The planet does not care where you build your building, only how close it gets to zero carbon. Climate change is a global problem, whilst regional benchmarks can be useful for comparing similar buildings in the same area they can produce unfair results.  For example, a house built in a low carbon grid area (e.g. Brazil) may have emissions of 2 ton/person/year.  This may only be a small improvement against the average Brazil house as they both have the benefit of a low carbon grid.  Conversely a building in WA may have higher emissions (say 3 ton/person/year)  but despite having higher emissions than the Brazil case could show a larger improvement against the average WA house.  A single benchmark is the only way to give correct credit for the true sustainability performance of a building.

Before getting into the nitty gritty, it’s important to understand the purpose of the eTool benchmark, which is:

  • To establish a common measuring stick against which all projects are assessed so that any project can be comparable to another.
  • To create a starting point, or “average, business as usual case” from which to measure improvements.

Benchmark Form and Structure

The benchmark has been created to represent an average dwelling built in a developed country, the statistics for a range of developed countries have been population weighted and combined into a single theoretical average dwelling.


The statistics used in the benchmark are based on data obtained for each country. The construction type and dwelling size statistics take new build data wherever available, as this data is generally reliable and represents a picture of the way buildings are currently being built across the developed world. For residential buildings there is a mix of houses and apartments. This is the latest breakdown of the new dwellings density mix across the countries considered in 2010:


The occupancy is calculated by dividing teh countries population by the number of dwellings to give an average. This is weighted by population to give a global average of 2.52.
For the single dwelling element (59% of our average dwelling) a building structure has been modelled taking a cross section of commonly used construction techniques. In this instance, the data was obtained for U.S.A.  The U.S.A makes up the largest proportion of new housing in the developed world and is considered to represent a fair “average house.”  Construction techniques are unlikely to differ significantly enough to impact on the overall modelling, whilst brick houses may be more common in the U.K. and Germany, timber framing is far more prevalent in Japan and Sweden.


A similar approach was taken with windows, internal walls, floors and roofs. The vast majority of those installed in new builds across America and Europe are double glazed and allowances have also been made for the smaller proportions of other window framing options currently in common use.


For the multi-family dwellings, a standard concrete frame structure has been taken with one level of car parking and typical auxiliary and common layouts, such that the apartment living area represents approximately 50% of the total floor area of the building.  The total impacts of this building have been weighted on a per m2 basis and 56 m2 has been added to the model to represent the apartment element.

Benchmark Operational

Existing data has been used for operational energy, and arguably new build data would be preferable, but total existing data is generally a lot more robust (and readily available). Whilst new build energy figures were available for some countries, the figures tend to be from modelling completed for regulatory purposes and are therefore theoretical. In many countries there is a perceived “performance gap” between modelling results and actual consumption mainly due to differences in occupant behaviour, but also because of limitations in software and methodologies used for the modelling. The hope is that there will be continued industry effort towards monitoring of new build housing performances. Until further data in this area is available, we have a robust snapshot of how average buildings are currently performing by taking existing housing data.

The data for total residential fuel consumption was divided by the total number of dwellings in each country analysed. This was then weighted according to population to give a final figure for the average energy consumption of a developed country dwelling.


End-use percentage estimates were then used to determine where this energy is being used in the dwellings.  Again, U.S. data[ix] has been used to represent the average.


Other impacts such as appliances and cabinetry and finishes have also been included by the estimated proportion of dwellings estimated to include these.

The global average water consumption is considered fairly consistent across most developed countries with America and Australia having higher water consumption due to larger garden sizes.  A conservative nominal 169l/person/day has been assumed for water supply and treatment.


[i] Populations by country 2010

[ii] Characteristics of New Housing U.S.A

[iii] Statistics Bureau Japan

[iv] EU Odysee Data 2008 downloaded on 11.7.2014

[v] Australian Bureau of Statistics Average floor area of new residential dwellings 2012

[vi] U.S. Energy Information Administration – Annual Energy Outlook 2014 – Energy Consumption by Sector and Source,ref2014-d102413a

[vii] Odysee energy database for EU and Norway (2008) downloaded from in July 2014

[viii] Statistics Bureau Japan Chapter 10 Energy and Water

[ix] U.S. Energy Information Administration Residential Sector Key Indicators and Consumption,ref2014-d102413a




Future Grid Sensitivity


The standard assumption eTool makes when conducting an LCA is applying the current emission factor of the electricity grid for the specific region over the life of the building. While renewable energy source do not currently make up a large percentage of the energy grid, the cost of renewable technologies has fallen dramatically over recent years. The Australian government also has a legally binding obligation to reduce its emissions by 5% on 1990 levels, under the Kyoto protocol. The Australian government has also committed to an 80% reduction by 2050.

If the decreasing cost of renewable energy trend continues and becomes competitive with coal and gas, the market will naturally shift away from fossil fuels, particularly if fossil fuel subsidies recede. There is also a small but growing consumer demand for more ethical electricity tariffs. This shift of energy sources into the electricity grid opens a potential for a change in the way grid emissions are calculated with life cycle assessment.

Modelling Decarbonisation

Presently in eTool we assume that the grid fuel mix remains at today’s levels for the life of the building. Whilst this is a good conservative position, and drives the right behaviour in terms of energy efficiency, it may divert some focus from other areas of the building, which may be more important if a more realistic future scenario of grid electricity impacts are used.

In response, we have created two other grid emission factors: a 2050 grid and a 2030 grid. The 2050 grid assumes an 80% reduction in the current grid intensity. The 2030 grid takes the average grid intensity over the next 40 years, assuming a linear move towards 80% renewable generation by 2050. The modelled reduction in CO2e intensity is achieved by:

  • Eliminating the most carbon intensive fuels from the current Australian electricity mix and replacing these with a combination of renewable sources, and
  • Increasing the thermal efficiency gas powered generators from 34% up to 50% (implementation of combined cycle turbines)

The fuel mixes and assumed thermal efficiencies for the different grids modelled is shown in Table 1. There are a few flaws in this method that we need to declare: Firstly, the scenarios assume reductions in CO2e intensity of tailpipe emissions only. It does not account life cycle emissions for electricity, which includes impacts associated with fuel extraction and transport upstream from the power plant as well as downstream impacts associated with transmission and distribution. Secondly, if we accepted that this would be enough to meet the 80% reduction in emissions required, the demand for electricity (or energy in general) could not increase. If there is an increase in demand, we would need to further reduce the intensity of Australian emissions and the target is on absolute GHG pollution, not pollution per dollar of GDP, per capita or per kWh. Nevertheless, we think the approach is suitable for the purposes of illustration and discussion, which is the goal of this technical article.


Table 1: Modelled Grid Fuel Mixes

Life Cycle Impacts of Residential Buildings

The graph below illustrates how the lower grid scenarios impact on a single residential dwellings life cycle emissions.  Proportionally, embodied emissions have a much larger impact than operational as the grid de-carbonises.

annualised GHG


Reconsidering Design Decisions

Generally speaking, there will be a move toward electric based solutions as the grid de-carbonises and the impacts of electricity become competitive with gas. A few recommendations that we typically apply to residential dwellings are shown for the different grid scenarios below.

Design decisions

In this instance, the annual CO2e savings associated with PV have more than halved in the 2050 scenario. Savings from embodied impacts in materials become much more important as the grid decarbonises and materials make up a larger proportion of a buildings CO2e. Moving to fly-ash concrete or replacing carpets gives greater savings than installing a gas hot water unit, which under todays grid scenario would ordinarily provide significantly more.

It’s important to note is that while the transition to a low carbon grid will likely occur incrementally over the coming years, the embodied impacts of the materials are locked in from the day of manufacture. Providing that the grid does decarbonise, material choice can be considered to be equally as important as operational energy, especially when dealing with buildings with a long design life.

What about the gas grid?

We have yet to add a CO2e intensity for future gas grids but watch this space.  There is potential for a reduction in the gas grid emission factor with more input into the gas grid from landfill collection and anaerobic digestion. Then again, potential impacts of shale gas fracking will also need to be considered.

The technologies that make up a dwellings services (cookers, boilers, heat pumps etc.) typically have a lifespan of no more than 20 years. Our approach at eTool remains to recommend the lowest carbon solution based on today’s grids with the assumption/hope that they will be replaced with whatever the lowest carbon solution happens to be in 20 years time.

The future may also bring an appropriate price on carbon and studies show that $150+/tonne reflects the true cost of climate change (social and economic cost), which will drive behavior. For example, a gas hot water system is significantly lower in carbon emissions today but in 20 years time when it is replaced, the electricity grid may have decarbonised such that a heat pump is now the low carbon option. Perhaps the occupant will be further incentivised by the price of a renewable electricity grid versus finite gas with a high carbon price.

What about Materials Future Impacts?

The manufacturing of some materials will decarbonise over the coming years, such as the use of biomass in the heating processes in cement production. However, for a building constructed today, the key structural elements of a building such as the impacts associated with the concrete or steel are locked in on the day of construction. The recurring impacts of replacing high carbon materials like plasterboard and carpet may also decrease as the economy de-carbonises. For some elements, this may be due simply to using renewable electricity in the manufacturing plant. For others it may require something more innovative such as developing sheep food that does not make them burp and fart.

There is a high level of uncertainty associated with future impact intensities for the system processes and materials making up a buildings use phase. For example, as Australia’s economy de-carbonises, the impacts associated with energy inputs, maintenance, replacement, repair, water use, and transport will likely decrease (particularly with regard to global warming potential). This has not been accounted for in the analysis. One could potentially model the effects of this parameter on GWP alone as we do know Australia’s current commitments to reduced greenhouse gas emissions, however, even this is very speculative as we do not know how the economy will decarbonise (through efficiency, reduced growth, alternative fuels, renewable energy sources or other mechanisms). The building energy inputs, and the fuel mix for manufacturing products used through the building life span has therefore been assumed constant, and set at today’s values throughout the modelled life cycle of the building.

What else might change?

Australia has been seeing first-hand the effects of climate change for a number of years. The meteorology department has confirmed that 2013 was the hottest year on record experiencing a greater number and intensity of heat waves than ever before. Even if global CO2e emissions are kept within the threshold for a 2 degree global rise in temperature, we will still need to adapt to the climatic changes that have resulted from our current emissions. The Garnet Institute makes the following predictions regarding changes to climate in Perth assuming no mitigation:


–          4 degree rise in average temperature in Perth,

–          56% increase in number of days over 35 degrees by 2070

–          15% – 45% reduction in rainfall in Perth by 2070

–          15 – 65% increase in number of days with “Extreme fire risk”


In the best case scenario with emissions stabilising at 450 ppm, there is still a 2 degree rise in average temperature across most of Australia. The reality is that we have already passed 400ppm and 550ppm (3 degree rise) is realistic. To adapt to these changes we will see a greatly increased use of air conditioning across all building types to maintain thermal comfort.


-Researched and written by Pat Hermon 


Research Sources




Brown Paper Background

LCA Design Life and Functionality

Why This Post?

Well, it turns out it’s REALLY important. My eyes opened to this on the first life cycle assessment we conducted four years ago now. I probably didn’t realise how important it was until more recently though.  The crucial moment was when we did some back of the envelope, top-down carbon budgeting to understand how much greenhouse pollutions our buildings could push into the atmosphere and still enable a stable climate. And this is where it gets interesting. The workings to our rough carbon budget for buildings are here and they throw out a fairly large challenge. In fact, for residential buildings, we need to go net zero operational carbon, and then reduce the remaining embodied emissions by nearly 90%.

Often when you hear the term embodied energy, embodied carbon or embodied impacts, it’s associated with materials choices. Or at least that’s the normal approach to reducing embodied impacts. But there’s an elephant in the living room that’s not being addressed, and this post discusses that. If you don’t want to read about it, sit back and enjoy this video (apologies for the less than professional sound quality).


Some LCA Basics

Life Cycle Assessment isn’t just about measuring impacts. One of the key elements of ISO 14040 is to consider the “Functional Unit” of the object of your assessment. The functional unit enables comparisons between variations of the product or services. In the case of buildings, it would correct for things like design life and size. Inherently, it’s correcting for the function of the building. And the formula for the impacts of a building hence becomes:

Life Cycle Assessment Impact Equation for Residential Building

Life Cycle Assessment Impact Equation for Residential Building

As mentioned above, most people focus on reducing the impacts when trying to improve building environmental performance. In reality though, it’s the denominator that often has the most effect on the impact of a building. And this stands to reason. If your building houses more occupants, or lasts longer, it’s providing more benefit for the same initial and disposal impacts (construction and demolition).  As mentioned in a related post here, we actually need to reduce our embodied emissions by nearly 90% to hit a sustainable level of GHG emissions.  So we need every bit of help we can get, and some focus on functionality and design life presents us with some very low hanging fruit.

Design Life

Extending design life is a brilliant way of improving the impacts per functional unit for a buildings. This is because most maintenance, energy and water inputs are pretty constant over the building’s life, where as the initial materials, construction, demolition and disposal impacts are quite independent of design life. For residential buildings in Australia, for example, these initial and end of life impacts total approximately 25% of the total life cycle impacts. So, by doubling design life without any change to energy efficiency, you can reduce the overall impacts of your building by over 12%.

How to Influence Design Life

In order to answer this question we really need to think about what is driving demolitions. There are two good surveys that answer this question quite well. One is from the US and the other Australia. They compliment each other in their answers. Here are the results:

US Study Conducted By Athena:

Reason for Redevelopment Proportion Categorised Reason Proportion
Area Redevelopment 35% Not Related to Durability 61.3%
No Longer Suitable for Needs 22%
Code Compliance Too Expensive 2%
Socially Undesirable Use 1%
Maintenance Too Expensive 0%
Changing Land Values 0%
Out Dated Appearance 0.90%
Lack of Maintenance 23.80% Lack of maintenance / neglect 26.4%
Other Physical Condition 2.60%
Structural or Material Problem 3.50% Durability Issue 3.5%
Other 2% Other 8.8%
Fire Damage 7%

Athena, Demolition Survey – Building Service Life Study – Phase Two

There seems to be a surprisingly large proportion of buildings that are being redeveloped for reasons other that structural integrity. So, building strength and durability seems to be only part of the design life story. It gets a lot more interesting when you read this study further, as it turns out the longest lasting buildings are actually timber. This was counter intuitive to me, I would have expected the steel and concrete buildings to be lasting longer than the timber ones. The other interesting thing was that there seems to be a hump that a building needs to get over at the 30-50 year mark, and once it’s over that, it’ll last a long time.

Service Life of Structure Type


The Australian survey supports the theme that durability is only part of the story.

Reason for Redevelopment Proportion
Demolished for Site Redevelopment 58%
No Longer Suits Owners Needs 28%
Other 6%
Building Becomes Unserviceable 8%

Dynamics of Carbon Stocks in Timber in Australian Residential Housing

Redevelopment Probability

These studies suggest that the durability of a building only plays a small role in predicting service life. Other factors, predominantly redevelopment pressure, are actually more important. The strategies to counter this are relatively simple. I’ve listed a few below:

  • Increase density compared to surrounding suburb through:

– Building value : Land value ratio
– Maximise yield

  • Diversify lot ownership, which increases difficulty for redevelopment in the future
  • Design quality (create timeless character by ensuring house is designed for the site and surrounds)
  • Enable retrofitting (enable occupant density to be increased or building use to be transformed easily without demolition)

Other strategies that assist in extending the service life of the building (or materials) include:

  • Ensure appropriate materials are used to weather any likely natural disasters in a region (e.g. fire)
  • Where redevelopment potential is very low, focus construction methods
  • Design for deconstruction (extend materials service life beyond the building)

We should be thinking of buildings as permanent features, that may stand for many centuries. Whilst this would be a paradigm shift in Australia, there are countless examples of suburbs within the world’s major cities where average design life of existing structures would be well in excess of 100 years. These are cities like London, Paris and Rome where this resilience to redevelopment is in itself the appeal of these cities. There are still pockets of historical buildings in Australian cities also, and our aim should be to promote this approach to the extent that it become the norm.


Increasing functionality is perhaps slightly simpler. It does require buy-in from the owner. In the residential context it really comes down to increasing occupancy within the same space. This doesn’t necessarily mean sacrificing life-style. Very well considered design will yield efficiencies in ensuring that every square metre of floor space is well utilised. Integration of stairs, corridors, studies, entertainment areas etc into bedrooms or living rooms are examples of efficient design. It also pays to compare our current residential functional average to that of our past, and also other countries. The chart below shows that over the last 35 years, Australia has trended badly in terms of environmental sustainability in relation to functionality of residential buildings. During this period, the average size of new buildings has significantly increased, whist the occupancy per dwelling has dropped. It’s encouraging to see a recent reversal in this trend, and we hope it continues.

Australian Residential Building Functionality TrendsWhen we look at he space per person, it’s increased from 54 to 96 square metres.  Compare this to the average space per occupant in the UK of 32 square metres and it’s clear that we have some wiggle room in this area.

In commercial buildings, there’s very good financial incentive for improving floor plate efficiency as it means greater rent. Small changes can yield big uplift in rental revenue. Intelligent strategies to improve floor plate efficiency include:

  • Sharing services between floors
  • Optimising lift size, speed and number
  • Minimising services risers
  • Minimising circulation ways

The common areas associated with large apartments or office buildings are also very worthy of attention. In Australia particularly, car parks often amount to 25% of total floor space or more. This is a huge burden on the useful floor area of the building, not only in terms of embodied impacts, but also operationally, due to lighting and ventilation requirements. Currently, car park efficiency is an area that doesn’t receive a lot of attention. We have yet to see a design brief where a developer has stipulated a target floor area per car park. Good practice internationally is 20 square meters per car space, and this is with a normal 90 degree layout. If the car park is large enough to accommodate loop, by moving to 45 degree angle parking the space requirements can be reduced even further. This is enabled by reducing the required space to pull in and out of the park to a single lane for 45 degrees nose-in parking, whereas 90 degree parking requires two lanes. It’s not uncommon to see car parks in Perth buildings requiring 30 square meters of space per car park, so there’s huge potential in this area for efficiency improvements and cost gains. Could that three level basement car park be optimised and reduced to two? Ask the question and refer to some international benchmarks on car park design, you might be pleasantly surprised.


The most frustrating thing about all these great opportunities to improve a building’s design life or functionality is that we rarely get to help people do it. The reason is, it’s usually been designed by the time we’re engaged. There’s a nice chart, a version of which is below, that explains how as a project progresses from brief to concept to construction and onwards, the ability to influence it’s environmental performance drops off sharply. This post effectively explains a bit part of the reason why. There are other design opportunities that also need early consideration to become feasible as well. We recognised this pretty early on at eTool and developed way of running ‘scoping study’ LCAs to help design teams identify and reduce environmental impact ‘hot spots’ in their concept designs. We’ve taken this a step further now by offering a target setting service. We can help a design team develop performance targets for their building before a concept design has even been dreamt up. All we really need is a draft brief and we can profile the life cycle impacts of a normal approach to delivering the intended function of the building. We then use this model to simulate improvements that the owner and design team want to target, these can include design life or functionality improvements. Early feedback on this service has been great, get in touch if you want more information.

Building Life Cycle Environmental Influence





Brown Paper Background

eTool Residential Benchmark For Australia

Before getting into the nitty gritty, it’s important to understand the purpose of the eTool benchmarks, which is:

  • Establish a common measuring stick against which all projects are assessed so that any report is comparable to another (for the same type of project).
  • Create a starting point, or “average, business as usual case” from which to measure improvements.

The benchmarks are not an average of existing stock but rather an average of new stock. Hence any efficiency requirements etc in the Building Codes etc are taken into account. When comparing to the benchmark, the target is pretty simple. Effectively Australia has to drop it’s GHG emissions by about 90-95% on a per capita basis for us to become sustainable global citizens. With this in mind, what we should be trying to do is drop our building’s emissions by 95% against the benchmark to ensure the building is stabilising the climate.

Creating the business as usual benchmark is pretty complex. For residential buildings in Australia there is a broad density mix from detached through to apartments. This is the latest breakdown of the new dwellings density mix in Australia (from ABS) over the last two years:

DetachedSemi DetachedLow Rise ApartmentsHigh Rise Apartments
Proportion of New Dwellings61%13%7%19%

For each of these density types, eTool have formulated a BCA code compliant building. We have then created a nominal statistical mix of  floor areas to match the average new dwelling size in Australia (214m2). In this way we come up with a “dwelling” that is a mix of densities and matches the size of the average Australian dwelling.

A similar approach is taken for operational energy. In this case we first research the most up to date residential energy estimates for Australia.  This data comes from ABARE Energy in Australia 2012. It gives us guidance on the total energy used per household (existing housing stock) in Australia and also the fuel mix split (electricity, gas, wood etc). We then use other end use percentage estimates to determine where this energy is being used in the dwellings.  The most commonly quoted breakdown of household energy use in Australia is from the “Your Home Technical Manual” which is actually a reference to the “Energy Use in the Australian Residential Sector, 2008”.  This report is commonly referred to as the “Base line report”.  This report itself actually states:

The study identified a paucity of end-use data for residential energy use in Australia, particularly in regional areas. Some of the appliance energy consumption estimates used in this study rely on research that is 15 years old or, alternatively, on work undertaken in New Zealand. 

The study recommends an comprehensive end use energy monitoring program which we believe is being undertaken. Until the results are out we’re a feeling our way in the dark a little.  Not withstanding this, the study is useful to guide the decisions about where we’re using our energy. To verify the Base Line Report figures we also took some state government studies (eg Sustainable Energy Development Office in WA) and statistics from other countries (notably the BRANZ HEET study and also stats from the US). The largest unexplained discrepancy seems to be in the estimates for heating demand.

The Base Line Report suggests that 38% of total end use energy in Australia homes is dedicated to heating and cooling purposes.  This seems very high given the following facts:

  • The comprehensive HEET study from BRANZ in New Zealand (a much colder climate, and one dominated by heating requirements) only calculated 34% of end use energy dedicated to thermal performance.
  • The WA SEDO estimate for thermal comfort energy demand is also much less, hence it’s hard to believe the additional demand is due to cooling.
  • A large percentage of Australia’s population (Perth, Sydney and Brisbane) all live in quite mild or warm climates where heating would not make up more than 50% of the thermal control energy demand (and less still of the actual end use energy demand)
  • Heating is the most end use energy intensive thermal comfort mode as cooling typically utilises either apparent cooling methods (evaporative or fans) or heat pumps, both of which have effective Coefficient’s of Performance of 2.5 or more. This means for every one unit of energy input, 2.5 units (or more) of heat is dissipated of pumped from the dwelling when cooling. Heating on the other hand requires more energy than the actual heat load demand theoretically required to heat a space (or at least the same amount). This is mainly due to flue losses.

The high estimate in the Base Line Report may be linked back to the ABARE Energy stats which are also questionable. The Energy in Australia 2012 document from ABARE gives a biomass figure for residential energy use that equates to 6280MJ / household /annum.  When this is calculated in terms of mass of wood, it works out at 400kg of timber per household in Australia.  Even if one in every 5 houses (studies suggest it’s more like one in every 10) is using a wood heater that was their primary source of heat, that’s 2t of wood per annum they would need to be burning in order for the ABARE data to reconcile. To give you an idea, an average small box trailer full of wood is about 250kg. We’re not convinced there’s 2 million households in Australia receiving 8 trailers of wood per annum to heat their homes. The BRANZ HEET study further supports the proposition that ABARE have overestimated biomass consumption in the Australian residential sector.  BRANZ calculated that each wood heater uses 4,500kWh (one tonne) of wood per annum.

Without making any adjustments to either the end use demand figures, or the top down supply figures the numbers don’t reconcile very well. For example, trying to “fit” the biomass, gas and LPG energy into the end use break down “squeezes” electricity out of the hot water and space heating categories. There simply isn’t enough low grade heat requirements in dwellings to account for all the biomass. However, when we aligned the biomass use predictions with BRANZ, and adjusted the demand figures to better match some of the competing studies we got good reconciliation.

This also supports the total residential demand estimate in the Base Line Report which is quite a bit lower than the ABARE stats.

Once we knew the amount of energy the existing housing stock were using, we then determine how this would differ in new dwellings.  Some energy use would remain pretty static (eg appliance use and refrigeration). Lighting, hot water and heating and cooling have relatively new BCA code requirements focussed on energy efficiency. For these end categories appropriate adjustments were made to account for the newer technologies and associated demand.

Heating and Cooling (Thermal Control)

The heating and cooling energy requirements are the most complex, as there are very few stats on what equipment is being deployed in new houses. The NatHERS system does help this situation and we make an estimate of the deployment of heating and cooling technologies in the current housing stock as follows:

  1. Estimate the heating verse cooling loads for buildings in the top 20 populous NatHERs climate zones (85% of Australia’s population). This works out to be 60% heating and 40% cooling.  
  2. Estimate the efficiency of each type of heating and cooling technology
  3. Estimate the deployment of each type of heating and cooling technology
  4. Adjust estimates such that total energy consumption matches our adjusted ABARE figures and the split in thermal demand matches the NatHERs weighted average for Australia

This then informs our decisions about what people are likely to choose for new houses.  The summary is found in the following tables:

Electric Heat PumpElectric Fans or Evaporative Coolers
Existing Stock Cooling Demand50%50%
New Housing Stock Cooling Demand60%40%

Electric Heat PumpElectric RadiatorsGas FluedGas Internal HeaterWood Heaters
Existing Stock Heating Demand20%10%17%51%2%
New Housing Stock Heating Demand35%0%20%40%5%

For each major BCA climate zone or population centre then simply divide the NatHERs energy demand estimates for a 6 star dwelling for the building between these categories and apply appropriate efficiency or COP figures to determine what the end use energy demand will be.

Hot Water

The building codes have now banned the use of electric resistance storage hot water systems in all residential buildings apart from class 2 building (strata buildings). Some state governments also discourage the use of electric heaters in class 2 buildings. This has led to a huge shift from electric storage hot water heaters to gas, solar, and heat pump units. This is a great thing for reducing the carbon intensity of the delivered hot water to dwellings (see more explanation on hot water fuel types here).

Using the same reconciling procedure between the end use energy estimates and the adjusted ABARE data we get the following mix of fuel uses for meeting demand in Australian existing housing stock:

Fuel Contribution to Water Heating Demand of Existing StockFuel Contribution to Assumed Water Heating Demand of New Stock
Natural Gas and LPG77%79%

Note, this doesn’t imply that 77% of water heaters are gas fired, it implies that 77% of energy used by water heaters is gas. The difference is that gas water heaters have lower efficiencies than electric resistance heaters (99%) or heat pumps (approximately 270%). With a gas water heater, depending on the age of the heater, it may be as low as 50%, and won’t get much better than 85%. So the mix of heaters installed in existing buildings is actually more slanted towards electric.

New buildings will tend more towards gas due to the current BCA requirements. With this in mind, we’ve used the figures in the right hand column for the split in fuel use for new dwellings.

One Plant Framework

The One Planet Living Journey

Cundall is the world’s first consultancy to be formally endorsed as a One Planet Company by sustainability charity BioRegional. In this presentation Simon Wild will talk about how Cundall have achieved this endorsement including some of the challenging targets we have set against the 10 One Planet Living principles, originally developed by WWF and BioRegional. Mark Pitman will then explain how the have approached this in Perth and discuss how the One Planet Living Principals can apply to Western Australia.

During this seminar, you will hear about the successes, failures, lessons learnt, obstacles so far, and the challenges ahead to run a business within the resources of a single planet.

Attendance of this event will earn 1 GBCA CPD Point

When: Thursday 14 March, 2013 at 4:15 PM (WST)

Where: Level 1, 40-44 Pier Street, Perth

Tickets: Register here


Update: Quantifying the benefits of the Sydney Harbour Bridge

The Sydney Harbour Bridge is the world’s largest steel arch bridge and acts as a passage for rail, vehicular, bicycle and pedestrian traffic between the Sydney central business district (CBD) and the North Shore. For the last 80 years, the bridge has been an international icon of Australia and all the social benefits associated with it are immeasurable. But what about all the steel, concrete, manpower and all the other impacts involved with the construction of the bridge. Has it paid itself off from an environmental perspective?

The material list includes 53,000 tonnes of steel, mostly imported by boat from the UK, 95,000 cubic metres of reinforced concrete and 18,000 cubic metres of granite that was transported 300km from the North of Sydney by specially built ships.

Using historic Australian records of the construction of the bridge, an eTool LCA was conducted to quantify and compare the results and benefits for both society and the planet.

Here are some interesting results:

Carbon impact of materials is dominated by imported steel for the arch followed by concrete for foundations.
Assembl­y impacts are very low when compared to total construction impact due to the use of cranes and manual work (6 million hand driven rivets!)
Transportation impacts are associated with materials transportation, especially the 79% imported steel from the UK.
Recurring painting maintenance and repair work represents only 6% of total embodied impact and will significantly increase bridge life.
Global Warming Potential (tonnes of CO2e)

Materials 270,693 83%

Assembly 6,499 2%

Transport 27,519 8%

Recurring 20,295 6%

Total 325,006

The predicted design life of the bridge used in the LCA was 300 years. This is another interesting topic because since the bridge is built with independent steel structures, the parts that present structural problems that can’t be repaired on site are replaced with new ones.

So, using eTool LCA results we were able to compare the embodied carbon impacts of the bridge with the operational carbon savings in reducing distances and fuel combustion.

The distance from Cammeray to Sydney passing through the bridge nowadays is 7 km and the route before the bridge via Gladesville was 17.6 km. Calculating CO2 emissions associated with fuel combustion savings over all these years and the average amount of vehicles crossing the bridge everyday, it represents a total savings of 11,850,720 tCO2e. The embodied impacts of construction achieved a carbon pay off due to transport fuel savings around 1955, and since then with the growth in transport across the bridge, have been repaid a further 35 times!

Whilst researching the LCA, we had a chat with Peter Mann, the asset manager of the bridge, who thinks the bridge will last another 300 years under the current maintenance regime. The bridge will potentially pay itself off a couple hundred times by then, which is an incredible environmental payback on an infrastructure project.

This is a great example of just how powerful LCA analysis is when evaluating infrastructure.
eTool LCA was designed to be totally scalable and used in any project from infrastructure to commercial and residential.

Contact us for more information about designing with eTool and getting the best outcome for your next project.

This assessment was conducted by Henrique Mendonca.

An update – Is the LCA on the Sydney Harbour Bridge too simplistic?

Absolutely!  Conducting an LCA on something as complex as the harbour bridge is much more complex than assessing a single product or building.  The reason being is that its influence is far reaching.  In a simple product LCA, practitioners will normally use an attributional method of assessing impacts.  In the case of a large piece of infrastructure that has far reaching influence, it’s more appropriate to use consequential analysis (see this article for more info ).

We definitely simplified the assumptions around the consequences of the bridge being built verse not being built.  We assumed the vehicle movements from north to south would not have significantly changed with or without the bridge.  This is incorrect for a number of reasons:

  • The bridge may have actually encouraged people to buy and use cars because it made their use even more attractive than before the bridge was built
  • Without the bridge, people may have chosen an alternative transport method (eg. ferry) or reduce their trips across the harbour because the car trip was too inconvenient via the long route.

However, after conducting this simple analysis, the advantages of the bridge were so clear that making further assumptions about how the bridge has influenced the above behaviour didn’t seem worthwhile as it is very unlikely it would have changed the overall result.  It may have doubled the payback period, but would not have changed the result from net positive to net negative.

The other part of the analysis that is quite important here is the forms of transport we didn’t mention. We just assessed the impact of reduced car use.  We didn’t assess the even greater efficiency advances associated with train, tram (up to 1958), bus, bicycle and pedestrian use.  In fact, nowadays, nearly 20% of people crossing the bridge daily are not travelling by car.  Furthermore, there have been significant policy changes that have impacted the bridge’s influence on sustainability. Originally the bridge had 6 vehicle lanes, 2 tram lanes and 2 train lanes;  the trams more than likely carried more passengers than the vehicle lanes during their tenure.  That’s not to say trams and trains (driven by largely coal fired electricity) are the silver bullet to sustainable transport either, however they are a vast improvement on typical car use.

Was there a more sustainable option?

Of course, for example, if in 1923, instead of initiating construction of the bridge we had been able to halt car sales and development of transport infrastructure we could have avoided an incredible increase in carbon emissions in the Sydney region due to transport. Perhaps a bit extreme? This debate is a big can of worms, and halting development isn’t actually a prerequisite of sustainability.

It turns out that due to education and health (very nice by-products of development) the human population on earth is set to stabilize at about 9 billion people.  (

At that level we could afford to emit about one tonne of carbon per person per year and the earth would be able to naturally draw this from the atmosphere. So our brief is to determine a lifestyle that accommodates 9 billion people on one planet.

For the harbour bridge, this probably would have meant two vehicle lanes (for buses and unavoidable commercial traffic run on biofuels and renewable electricity), an extra cycle lane or two, four heavy rail lines and four light rail lines (both run on renewable electricity).
So we have a few paradigm shifts to make before we reach this utopia (imagine it, it will be fantastic) but it’s not unrealistic over the next 80 years of the harbour bridge’s lifespan (think of where the world has come in the first 80 years since the bridge was opened, it would have been very hard to imagine in 1932).  On another positive note, it’s possible that “peak unsustainability” per person has probably been surpassed in Australia, we are finally trending the right direction.

The Insulation Sweet Spot

How much insulation is enough?  If I double the R value, does that mean I halve my heating and cooling loads?  Unfortunately it’s just not that simple, increased insulation has diminishing returns in reduced heat transfer.  To explain this, first, let’s start with carefully defining R Value.  It’s a measure of resistance to heat transfer and can be stated as follows:

Using the above formula gives the R value in SI units which we will work in for the rest of this article.  To convert to US Imperial units, you need to times the RSI by 5.678.  Now lets use the above formula and apply it to an example of a wall. We want to calculate the heat transfer value, which will then give us the heating/cooling energy requirement for our heating/air-conditioning system and from that we’ll be able to work out the cost. The formula now looks like this:

The assumptions we are using are below, some of these are inflated to accentuate the potential savings:

  • Area of external wall: 100m2
  • Temperature difference between internal thermostat set point and external temperature: 15 Degrees C (quite a difference, either hot climate trying to cool or cool to cold climate trying to heat)
  • Coefficient of Performance (COP) of Heating or Cooling Device: 2.5 (relatively poor)
  • Assume that we are paying $0.25c for every kWh of delivered energy to the building
  • 24 hour average occupancy, so continual maintenance of desired temperature.

We’ll start with a single brick wall (RSI Value of 0.106) and then slowly increase the insulation to determine how much money we can save. Here’s how much the heat transfer reduces as R value increases:

As you can see, the reduction in heat transfer is huge, at least initially. In fact nearly 80% of the heat transfer is stopped with just RSI0.5 insulation. As you increase the R Value further the savings in heat transfer drop off significantly:

  • RSI0.5 to RSI1.0: 11% extra heat saving
  • RSI1.0 to RSI2.0: 6% extra heat saving
  • RSI2.0 to RSI3.0: 2% extra heat saving
  • RSI3.0 to RSI4.0: 1% Extra heat saving

So what about the effect to costs? See the following graph for the details on the heating and cooling cost savings for our conceptual building:

Once again, we see a very big drop off in savings as R Value increases. And these savings are potentially inflated, if the average internal temperature to external temperature difference was halved to 7.5 degrees C, we’d see these values halve also.
There is obviously a sweet spot somewhere between RSI1 and RSI4, probably around the RSI2.5 mark. Of course, this depends on the insulation costs, the cost of the structure to house the insulation and the design life of the building. For example, going from RSI2 to RSI4.0 may only require a small increase in insulation costs, but if the wall framing need to be increased in width by an inch, this could be quite costly.

The other important consideration here is that this is all based on theory. What is actually going to happen in an average building is probably going to further lessen the impact that your wall insulation has on your heating and cooling costs. For example, if you poked five small 100 x 50mm holes in the insulation of our conceptual house, depending on drafts etc, you’d probably reduce RSI3.5 walls insulated walls to the equivalent of RSI3.0.
In windy climates or pressurised buildings, this could be a lot worse. Similarly there are likely a lot of other easy wins to increase the actual performance of your house that don’t relate to your wall insulation, for example:

  • Glazing type (R Value)
  • Glazing area (lots of windows usually means lots of heat transfer)
  • Floor insulation (appropriate in cooler climates)
  • Floor ground coupling (appropriate in warmer climates)
  • Efficiency of your air-conditioning and heating system
  • Cost and carbon intensity of your energy supply source (eg gas verse electricity)

I hope this helps explain the R Value sweet spot.
For the control freaks out there who want to know exactly where that is for their particular building/climate/energy mix etc, get in touch!