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
I’ve heard its complicated why is that?
We need to reward recycling but also have to be careful not to double count the benefits (at the start and end of life for example). The approach under EN15978 is as follows:
- to reward “design for deconstruction” as the key driver that determines the net results over the whole life of a building
- to allocate economically, so if a product is a waste product at the end of the buildings’ life (there is no market for it, so it costs money to remove it from site rather than having some sort of scrap value) then any benefits associated with recycling that product are picked up by the next person who uses it. So essentially, recycled timber is all rewarded at the start of the building’s life. Recycled aluminium is all rewarded at the end (in net terms)
Allocation of reused products from other industries are also done economically, one example of this is recycled fly ash or blast furnace slag in concrete. Because Blast Furnace has some value, it’s not as attractive environmentally as fly ash
The rules for recycling allocation under the EN15978 methodology were initially somewhat mind-boggling for me. To understand them you will likely need to take a number of re-visits and you should try to wipe out any preconceptions you may have on recycling.
So how does it work?.
Lets start with what is included in the scope of En15978 first,
Note that Module D is actually a form of “System Expansion” and one could argue is outside of the life cycle of the building.
Before we look into recycling allocation further we also need to understand a few definitions.
Recycled content is the proportion of recycled material used to create the product, the global industry average recycled content of aluminium today is approximately 35%. This means that in 100kg of aluminium 35kg comes from old recycled aluminium and 65kg comes from new raw material.
Recycling rate is the proportion of useful material that gets sent back into the economy when the product comes to the end of its life. The global industry average recycling rate of aluminium today is approximately 57%. This means that in 100kg of waste aluminium 57kg will be recycled into new aluminium products and 43kg will be sent to landfill.
Closed loop recycling, whereby a product is recycled into the same product (e.g. steel roof panel recycled into steel reinforcement). The loop is closed because when the steel product comes to the end of its life it can be recycled into a new steel product (theoretically this can happen continually forever). Closed loop is more straightforward to calculate as the emissions are directly offset by the new product that would have been required to be made from scratch.
Open loop recycling is when the product is used to create something new (e.g. old plastic bottles recycled into carpet). The loop is open because the plastic now in the carpet required other material inputs to create the carpet and cannot be recycled further (if a process is developed that can continually recycle the plastic carpet then it becomes closed loop). We use economic allocation to understand the impacts that are being offset.
Now lets focus on a closed loop recycling example of a standalone 1000 kg of ‘General Aluminium’ modeled in eTool. Under EN15978 scope impacts under module D – Benefits and loads outside the system boundary are quantified. This includes closed loop recycling which is not directly related to the actual physical boundary or life cycle of the building.
The life cycle stages for the aluminium are shown below
Kg CO2e by LC stage for 1000kg of general aluminium
Hang on, the impacts are bigger for the 100% recycled content option???
Well, there is an initial saving in the product stage of 18,280 kg CO2e from using 100% recycled content aluminium versus using a 100% raw material. The no recovery option also gets a small advantage for transport of waste (C2) because landfill sites tend to be closer to a building than recycling sites on average. The no recovery option is also (very slightly) penalised for disposal impacts, if the aluminium is recovered it has 0 disposal impacts because it is sent to the recycling plant and these impacts are counted in the A1-A3 stage of the new aluminium product. The interesting result though is in the closed loop recycling. We have a credit applied to the aluminium that is recovered and put back in the economy. This is effectively offsetting the assumed extraction requirement for the new aluminium to be used in the (aluminium) economy – for example in the next building. Likewise aluminium that is not recovered causes a higher net demand for new aluminium. To determine the ‘credit’ or ‘penalty’ at the end of the building’s life, the net increase in new aluminium required due to the use of the aluminium in the building is calculated. In the 100% recycled content, 0% recovered the material is penalised by the equivalent mass of new aluminium which will need to be extracted to supply the next building.
Yes it may seem counter-intuitive but try to think of the world aluminium economy as a single life cycle entity. If everyone used only 100% recycled aluminium that has 0 end-of-life recycling rate (ie it ends up in landfill) then we would soon run out of recycled aluminium available. We would have to go back to using raw aluminium (maybe even start digging it back out from landfill!). By encouraging recovery of the aluminium EN15978 is trying to discourage the overall extraction of the raw material.
O.K. That wasn’t too bad
So far so good but it gets trickier! Lets imagine we have fully recycled content and fully recovered aluminium,
Well you get the best of both worlds – reduced product stage and closed loop credits right?
Wrong! Here is what happens….
Kg CO2e by LC stage for 1000kg of general aluminium
The minus CO2e credit at end of life can not be applied in this instance because you are already using 100% recycled aluminium. There is no material extraction in this case to offset and your end-of-life credit is 0. You don’t get penalised for the added extraction for the future building but you don’t get credit for it because that has already been given in the product stage. Under EN15978 there is actually a very similar amount of carbon associated with a 0% recycled/100% recovered aluminium scenario and a 100% recycled/100% recovered aluminium.
Whoa, that’s deep.
Its a tricky one and there is certainly an argument to say this is not encouraging the right behaviour but the emphasis on end-of-life treatment means that the impacts are accounted for and credit is given without double counting.
So what do we take from all of this?
Recycling content and rate is an important consideration in buildings but it is no silver bullet. Every little helps in sustainability though. Focus on the durability and deconstructability of the product over the recycled content which under EN15978 has a relatively small impact on the environmental performance.
*Note figures show are taken from eToolLCD September 2016
References: Recycling Rates of Metals, T E Graedel, 2011
As part of an overall environmental strategy stipulated by the State Government, LCA has been integrated into the design and construction of Perth Stadium. eTool produced life cycle assessment analysis in three stages forming part of the overall design strategy as outlined below.
Stage 1: An initial “Targeting Study” was completed during bid stages whereby two initial models were developed – an initial LCA model of Perth Stadium and a benchmark LCA model of the already constructed Etihad Stadium (Melbourne) which was considered a typical stadium build. From the outset, Perth Stadium was indicating an improvement over the benchmark due to the predominantly steel structure which is inherently lower in CO2e emissions compared to concrete structures. The targeting study also highlighted a number of CO2e hotspots such as food and drinks refrigerators which are typically left on between games. Controls to switch off non-perishable items between events were an obvious easy win and one which the design team was confident in being able to implement.
Stage 2: As the design progressed, further information became available and the models accuracy was increased and consolidated with bills of quantities. With steel and concrete contributing the majority of the embodied impacts, it was important that these elements were accurate. The refrigerant gasses for chillers and food refrigerators was also included which contributed over 2% towards the total CO2e impacts, with the Stadium seating also found to have very high recurring impacts. Strategies put forward included using a low impact refrigerant such as CO2 and specifying extended warranties for the seating in order to increase the duration of their useful life (hence lowering their impact).
Stage 3: The model was finalised to include all recommendations uptaken as well as final quantities for materials and energy modelling figures. The design team were able to implement the following:
Strategies to switch-off non perishable item fridges between events
Blast Furnace Slag replacement in some structural concrete elements
Extended Seat Warranty effectively prolonging the predicted lifespan of the seats
The State LCA requirements were as follows.
– a 7% reduction against the benchmark in product stages (A1-A5)
– a 5% reduction in Maintenance stages (B2-B5)
– a 20% reduction in Operational stages (B6-B7)
The LCA analysis was able to successfully show performance against these impacts and quickly develop effective strategies to meet the targets. The final design specification shows overall life cycle impacts of 7.68 tCO2e/seat/year; which when split across the planned 37 events per year results in impacts of 0.2 tCO2e/visit. This exceeds the targets with a
– a 9.1% reduction in product stages (A1-A5)
– a 8.1% reduction in Maintenance stages (B2-B5)
– a 32.2% reduction in Operational stages (B6-B7)
The study also highlights the importance of taking a Life Cycle approach towards targets. When targets are set for individual elements perverse outcomes can occur. For example, PV panels are very effective in reducing life cycle emissions in Western Australia, however in this instance they would negatively affect the maintenance target (due to the replacement of the panels). eTool recommends that a single whole of life approach is taken to ensure absolute environmental benefit is achieved.
With the tremendous uptake of residential solar PV installations all around the world, the next question that often comes to mind is: to stay grid connected or go off-grid? For most people who are concerned about environmental issues, they might be led to believe that completely weaning off our fossil fuel powered grid is the truest form of sustainable living. However, here at eTool we like to challenge people’s beliefs based on data from life-cycle analysis.
To start, let’s quickly look at the difference between the two systems.
A grid-tied system is connected to the utility grid. In new systems, there is only one meter that measures both in-coming and out-going power to the house. Power generated from the solar panels goes through the inverter which converts DC to AC which then used throughout the house. Any left-over power that is not used goes out to the meter where it is measured then fed into the grid to be consumed elsewhere. This system has no on-site battery storage so any solar power that is not used at the time it is generated will be fed directly out to the grid. When no energy is generated by the solar panels such as at night or on overcast days, power will be drawn back from the grid to supply the house.
An off-grid system means that the system has no connection to the grid at all. In this situation, battery storage is necessary in order to provide power to the house when there is no power generated by the PV system. An additional on-site generator may also be required as a backup in case the stored power runs out. In this system, the power from the solar panels goes through a charge controller or battery regulator then into the battery bank for storage. On demand, the power is drawn from the batteries through an inverter then to the house to be used. If the power stored in the batteries run out, a generator can be started to produce backup energy.
Carbon Intensive Grids
|AU Standard||Structure – timber + double brick|
Cooking – Electric
HWS – Gas storage
HVAC – Airsource heat pump (MEPS ave)
Lighting – CFL
Refrigeration – AU average
Water – AU average
In order to compare the systems, we will use LCA to quantify the impacts in CO2e. We assume that all other factors are constant such as water, gas and the carbon intensity of the grid. The table above shows the building structure and appliance specifications for a standard Australian detached home. Only the PV systems will change in order to better compare the difference between grid-tied and off-grid.
The graphs above shows the life-cycle carbon impact of a standard Australian home with no PV system installed. We can see that the life-cycle energy of the building takes up the largest portion of the overall impacts of the building. The graph on the right shows the end-use breakdown of the standard Australian household’s energy use.
The blue column on the left in Graph 2 above is a standard Australian home with no PV. The red column is an off-grid system sized to provide 100% solar power throughout the year. This is a 15kW PV with about 100kWh of battery storage to provide backup power for 3 days while the green column is the grid-tied version with 15kW of PV without battery storage. The orange& dotted columns show the impact of a smaller off-grid 8.5kW PV system with 60kWh of battery storage. The dotted orange column has an additional backup diesel generator that provides 10% of the energy demand. The teal column on the right is the grid-tied equivalent with 8.5kW PV and no diesel backup or battery storage.
We can see that installing a PV system alone has a significant effect at reducing the CO2e impact of the building. Note that despite a near two-fold increase in the amount of PV, the life-cycle carbon savings in the off-grid system only has marginal improvement when compared to the grid-tied system. This is due to the high embodied impacts of the larger PV system which are underutilized in the off-grid system whereas in the grid-tied system all extra power generated by the over-sized system is fed into the grid.
In the graph above, we compare the category breakdown of the 15kW PV systems versus the AU standard home, we can see that while the life-cycle energy use of the solar powered homes have dropped significantly, the recurring impacts on the other hand have increased due to the impacts related to replacing PV panels and batteries.
Low Carbon Intensity Grids
In areas with cleaner grids, in this example I’ve used the Tasmanian grid (even though it is still connected to the NEM) – is a grid-tied PV system still relevant?
The graph above shows that although the proportion of savings is much less in a low-carbon grid, a grid-tied PV system still has a lower life-cycle CO2e impact compared to an off-grid system. In areas with cleaner grids, the embodied energy impact of the building becomes proportionately more important than the operational energy as shown in the graph below.
Best Practice Design
How about a house that is designed by someone who knows what sustainability is about? Let say they designed using low-embodied energy materials and didn’t install any air-conditioners – how would such a house compare? The low-impact or ‘best practice’ design building assumes that the occupants are more sustainably conscious and try to reduce electricity demand as much as possible in the choice of appliances they will use and are more likely to build with low embodied impact materials such mud brick. A detailed list of specifications in the ‘best practice’ house are listed below while still assuming Australian averages for water and refrigeration energy use. Based on these specifications, the off-grid ‘best practice’ home will need 4kW of PV and 48kWh of battery storage assuming 10% of the energy demand to be provided by a diesel generator.
|Best Practice||Structure – mud brick|
Cooking – Wood
HWS – biomass
HVAC – ceiling fans+wood pellet heater
Lighting – LED
Refrigeration – AU average
Water – AU average
PV – 4kW
Off-grid Backup – 48kWh battery storage + diesel generator
The graphs below show the global warming impact of a ‘best practice’ home on an Australian average grid the embodied and operation energy breakdown and the carbon impacts on a low-carbon grid. Even though the overall life-cycle carbon impacts of the building has dropped significantly due to the ‘best practice’ design, the results still indicate that being grid-connected is better for the environment in both grid situations.
In areas with carbon intensive grids such as Australia, it is important to help ‘clean up’ the grid by staying grid-connected with our PV systems. This is due to the fact that all the excess potential energy from off-grid PV panels is ‘wasted’ instead of captured to be used elsewhere. An off-grid setup will usually have a PV system that is large enough to meet most of the energy demand of the household throughout the year. This means that the system will be sized to produce enough power in winter but in summer when there is more daylight, the extra electricity generated by the system will be wasted.
A grid-tied system on the other hand is able to take advantage of an existing energy network and maximise the energy generation potential of their PV systems as any excess energy is fed back into the grid to be utilised elsewhere. This means that the embodied energy of the building can also be offset when the building produces more renewable energy than it consumes throughout its life.
A cleaner grid also means that other homes, offices and industries such as water desalination plants and manufacturers that use this cleaner electricity will be less carbon intensive. We all benefit from the knock-on effects of staying grid-connected.
For areas where the grid is already ‘clean’, the operational energy impacts become less significant from a carbon perspective but you’re still better to have grid-tied PV. Staying connected in a green-grid also helps avoid the additional embodied impacts from an oversized PV & battery storage system.
Bear in mind that there are other resources and technologies that haven’t been modelled here which may provide better solutions by taking the best of both systems. For example, hybrid systems combine the advantages of grid connection with battery storage to help moderate grid loads. To provide an efficient solution to large scale energy distribution, ‘Smart Grid’ systems that monitor and control the grid’s energy distribution and production is the way to go. Combine smart grids with hybrid solar systems and the economics and efficiency of renewable energy distribution and supply grid will be greatly improved. Nevertheless, the underlying message still points to the fact that staying grid-tied is the key in order to stay most sustainably relevant today and in the future.
This post is designed to guide design teams during early design stages prior to any form of drawing mark-up. It describes a pathway of continuous building improvement through easy low hanging fruit strategies to incorporation of renewable technologies and advanced design principles. As sustainability becomes engrained in the construction industry it is important that stakeholders maintain an understanding of what the market expects both presently and going forwards into a low carbon future.
Achieving Targets – The Basics
Generally a multi-residential apartment building built to BCA standards (electric hot water, 6 star Nathers and standard air conditioner) will have approximately the same impacts as the benchmark average dwelling (4.2 tonnes/person/year). They tend to be smaller (less space to heat and cool), have longer design lives and high occupancy (reducing the impacts on a per person per year basis). The chart below represents the life cycle Impacts of a typical multi-residential apartment building.
Typically there are a number of “low hanging fruit” design improvements that are low cost and low risk to implement. The measures focus on operational energy which generally makes up 70%-80% of the total life cycle impacts. The measures are detailed below for a standard apartment building with a mix of one and 2 bed apartments, please note these are indicative figures and will vary depending on final design, density, services and materials used.
|Typical percentage improvement|
|Gas hot water system||25%-30%|
|Lighting motion sensors/timers in common areas||6%-8%|
|Apartment Energy Monitoring||2%-4%|
|Behavioural Change Programs||2%-4%|
|Low flow shower heads (5l/minute)||1%-2%|
|Limit refrigeration space to less than 750mm||0.6%-0.7%|
|Ventilated refrigeration cabinetry||0.4%-5%|
With implementation of the above measures the building will achieve approximately a 37% to 45% improvement sitting at a Silver medal rating. To achieve greater improvements renewable technologies are needed.
|Renewable Technology||Typical percentage improvement|
|Solar Hot Water (1m2 per dwelling)||3%-4%|
|Solar PV (1kW/ 10m2 per apartment)||5%-7%|
The majority of medium rise flat roofs can easily accommodate the above with room left over for other elements such as flues and skylights. The low hanging fruit combined with some renewable generation will typically achieve around a 45-55% improvement.
Achieving Targets – Best Practise
For higher ratings to be achieved, there will need to be upwards of 1 kW and per apartment and over 10m2 of roof space available alongside the measures detailed above. This can require careful consideration of roof designs from the outside and in some instances, consideration of options off-site such as community owned solar PV farms may be required.
|Renewable Technology||Typical percentage improvement|
|Solar PV (2kW/ 20m2 per apartment)||10%-14%|
|Solar PV (3kW/ 30m2 per apartment)||15%-20%|
|Solar PV (4kW/ 40m2 per apartment)||20%-28%|
Roof Orientation for PV:
Once a residential building gets above 4 storeys, or a commercial building gets above 3 storeys, it will likely end up in a position where the solar technologies that are required are constrained by the roof space that is available. In this situation the design team should take roof design into consideration from an early stage and optimise it for solar panel installations. The following guidelines should be considered:
- By installing panels “flat” on a roof, many moor panels can fit because they do not need separating for shading.
- Shading from surrounding objects and buildings is an important consideration however it is rarely a problem in multi-residential buildings taller than their surroundings. PV can be very worthwhile even if partially shaded and can may still deliver significant carbon savings compared to other measures.
- For designing roofs in this situation, the following considerations should be made. Note that the below loss figure for varying orientation and pitch are applicable to Perth (latitude of 32 degrees):
- The orientation of the roof can significantly aid the amount of PV or Solar Hot Water that can be installed in the diagram above
– North facing panels at 32 degree pitch gives optimum energy gain over the whole year (100%)
– Dropping pitch to 5 degrees only results in a loss of approximately 9% (91% of optimal generation)
- If panels are to be pitched at lower than 10 degrees, consideration should be given to at least annual cleaning until it is proven that soiling is not effecting generation.
- If possible, avoid hips in roofs as these significantly reduce the amount of PV that can be installed. It is far better to pitch the roof in two directions only. Even pitching north and south in two directions is likely to result in a better overall result than in four directions. The south facing panels may generate less power per panel than the east or west, but more panels will be able to be installed because hips won’t have to be avoided and this will more than make up for the slight loss of efficiency in south facing panels.
- Very wide gutters can significantly affect the available roof space for solar collectors. Consider overhanging the roof structure over a required large gutter.
- Protruding services that break up the roof space should be designed if possible on the south side of the building. This reduces the losses due to shade for solar collectors across the whole roof.
- Roofs with multiple heights are complex due to overshadowing. If possible avoid this.
For solar hot water systems the same rules apply however slighting more consideration may be required to match demand with pitch, so a higher pitch to meet the higher winter water heating demand. This is not such an issue with PV as it can be fed into the grid when generation is higher than demand.
Some of the recommendations listed below represent paradigm shifts not only in actual construction but also in the marketing and sales strategies that may be required to ensure a developments viability. There may be times when it makes more sense to invest the money that would go into some of these expensive onsite solutions to other local projects that can deliver more value and higher CO2e savings. Examples of this may include Investments in street light upgrades, existing housing retrofits, solar panels on local schools and buildings, behaviour programs, community farms, bicycle infrastructure etc.
The more people a building can house the less impact per person that building will have. Furthermore for every person that is housed in a sustainable building that takes one more person out of the average, unsustainable building – moving society towards a low carbon economy faster.
Typical multi-residential buildings have approximately 50% of the total floor area dedicated to actual living space, the rest tends to get tied up in common areas, car parks, plant rooms etc. By minimising the common areas you reduce impacts on two fronts: living area available for the same volume of materials, and reducing the operational energy required to light and ventilate the common spaces (this can typically take up to 15% of the total CO2e emissions).
|ratio net dwellable area/gross Floor Area||Life Cycle Reduction in Emissions|
There are numerous ways that common areas can be reduced:
Space efficiencies can also be gained by increasing the number of stairwells whilst reducing the common walkway areas.
Although stairs are likely to be the more expensive option, this could be recouped by adding the spare hallway space into each apartment, in the example above this provides an extra 8.75m2 per apartment.
Typology (Beds and bathrooms)
Environmental impacts can be reduced through increasing the occupancy of the apartments themselves. Whilst 2 bedroom 2 bathroom apartments are fashionable, with good design that (rarely used) spare bathroom could be a third bedroom instead. This provides an increase in the overall sustainable living space of the building without impacting on the floor area being constructed
In many ways embodied carbon is equally (and perhaps more) important a consideration than operational energy. eTool LCAs will typically assume current grid intensities throughout the 100+ year predicted design life of a building. This means operational energy makes up around 80% of the total impacts. In reality over the next 100 years the grid will decarbonise and operational energy will contribute much less over time. The embodied carbon in materials on the other hand is locked in from the year the material is manufactured and transported to the site. There are many low impact alternatives to common materials in construction. Timber and CLT can be used in place of concrete and steel. Where concrete is necessary fly-ash or blast furnaces slag blends should be incorporated, these are waste products that can directly replace a proportion of the concrete thereby reducing its impacts.
Timber veneers and plywood should be avoided due to the high impact of the glues and resins used in these products. Plasterboard also has very high impacts. Alternatives such as plain hardwood, bamboo or MDF represent significant savings. IF plasterboard is to be used 6mm sheets should be preferred to 12 mm sheets with acoustic requirements met through insulation which is typically low in CO2e emissions.
Carpets (especially wool) should be avoided with cork or polished concrete finish preferable. If absolutely necessary carpets should be dark coloured (to avoid replacement through soiling) and plant based materials such as jute and sisal should be specified that have natural/non-synthetic rubber backing.
There tends to be little difference in terms of environmental benefit between CFL lights and L.E.D lighting Increasing natural light levels using solar-tubes, skylights or similar means less use of artificial lighting energy. Specifying lighter matte colours to surfaces such as the balcony, ceiling and walls will bounce light deeper into the dwelling thus increasing natural lighting. Light shelves in windows is another passive way to divert and bounce light deeper into the dwelling. Similar systems using adjustable louvres can also be used. Providing translucent shading material in addition to heavier curtains allow the option of diffused daylight to penetrate whilst maintaining privacy. The top of the windows is where light penetrates deepest into the dwelling, so it is important to ensure that this part of the window is not obstructed by drapery or blinds. Translucent partitions between rooms also allow light to be drawn into deeper rooms. Clerestory windows also provide a method of introducing more natural light into central rooms. Ideally these should be utilised with higher ceilings and high reflectance surfaces in order to encourage light to penetrate. In order to prove the value of these initiatives a daylighting simulation should be undertaken to ensure expense is not incurred for no benefit. This will likely make this recommendation hard to justify economically (there will be many far easier wins elsewhere in the building.
Gas cookers over electric
In regions with fossil fuel dominated electricity grids such as WA, gas represents a large advantage over electricity for providing energy to cook with. This is due to the heat and electricity losses associated with distributed power. Burning the fuel (gas) at the source eliminates these losses and is a more efficient way of using the fuel. The majority of gas cookers sold today include safety features that automatically turn off the gas when no flame is present. Rinnai has also developed the ‘inner flame’ technology that produces a flame that is directed inwards which is about 27% more efficient than standard gas stoves. The drawback to moving to gas cooking is that a gas pipeline may need to be installed. If the implementation of this strategy is outside of the project budget the developer may offer the strategy as an upgrade package for purchasers. This eliminates the need for upfront capital while promoting best practices and educating the public.
Or Induction cooktops
An all induction cook-top is an alternative that could deliver carbon savings over a standard electric cook-top. Induction cook-tops work by transferring electrical energy through induction from a coil directly to the magnetic pan. Only the area in contact with the coil heats up and therefore the cooker can be up to 12% more efficient than a standard electric conduction cooker. The controls on an induction cooker are also far more precise giving a greater range of cooking techniques.
Car Park Ventilation
By applying a detailed engineering design to the car park ventilation systems, it is expected that the fan run times could be considerably cut down especially when natural ventilation is utilised. Computational fluid dynamics would be utilised in this technique to determine how to best move air through the car park to maintain acceptable CO2 levels with minimum energy demand. Gains may also be achieved in reduced ducting. At least a 20% saving in ventilation may be achieved.
Biodigesters turn food and or human waste into gas that can be used in cooking. Although not well established in western countries this technology has been used for hundreds of years in China and India. Communal or individual systems exist that may be incorporated into an innovative building design.
The appliances that go into the building can make a significant proportion of the recurring impacts. Modern appliances tend to have fairly small warranty periods in relation to the lifespan of a building. TVs in particular can often not last more than 10 years. Ensuring that appliances are purchased second hand and those that are purchased new have a long warranty and are kept for as long as possible can provide significant carbon savings. In this recommendation we have assumed each appliances lasts twice as long as the standard warranty. Where appliances are installed they should also be of the higher MEPS rating bands for energy efficiency.
Modern 6 star dwellings in Western Australia need very little in the form of heating/cooling. The developer with sustainability in mind will provide only ceiling fans for cooling and renewable biomass pellet heaters for heating. Bio Where air conditioners are provided they should be single split units which can obtain higher efficiencies generally than multi splits. A COP/EER of 5 is exemplary.
Tri-generation, deep geothermal and shallow ground source heat pumps can also be appropriate in very large developments with high demands such as precincts with swimming pools. However they entail very high outgoing capital costs and the environmental benefit should be considered carefully against other technologies.
Most importantly swimming pools should be appropriate for the size of the development. Proportionally 50m2 pool shared amongst 100 dwellings will have 100x fewer impacts per dwelling than the same size pool provided for a single dwelling. Where pools are installed they should ideally be naturally heated through ambient air and install pool covers that contain the heat when the pool is not in use. Typically including a pool cover which can operate automatically or manually for 8hrs per day during the pools closed hours has a 28% saving in the pools heating energy demand. Pool pumps efficiency should also be considered carefully, high-efficiency pool pumps of up to 9 stars MEPs rating are currently available on the market.
Alongside solar thermal technology and low flow shower heads, an opportunity exists to warm the inlet temperature of the water by using a heat exchanger. Water exiting apartments in the sewerage drains will have a higher temperature than the normal inlet temperature of water coming into the building from the mains, particularly in winter. By passing the inlet water over the warmer outgoing water, the temperature can be increased. A 5% reduction in energy demand of the hot water system can be achieved.
For communal systems there will be significant heat losses in the pipe carrying the hot water around the building as well as from the individual water storage tanks. Based on the conservative assumptions of a 25mm pipe with 25mm of insulation (125mm total diameter) the heat losses are estimated to increase the hot water demand by 10%. Correctly installed 50mm pipework insulation could therefore reduce the losses through hot water pipe by approximately 5%.
The door is always open at eTool for questions surrounding design decisions. If a project is in concept phase we are happy to sit down for an hour and discuss potential strategies and targets. Full targeting sessions are also available at low cost to determine more accurately the costs involved in achieving design aspirations. Following this our full LCA will provide the most detailed environmental assessment available.
eTool recently changed from offering numerous fairly localised benchmark options to a single international average benchmark for each building type. The decision making process was interesting so I thought I’d quickly document it.
The purpose of the eToolLCD benchmark is:
- To establish a common measuring stick against which all projects are assessed so that any project can be comparable to another (for the same building type);
- To create a starting point, or “average, business as usual case” from which to measure improvements.
From the outset we’ve always understood that a benchmark needs to be function specific. That is, there needs to be a residential benchmark for measuring residential buildings against etc. The first point essentially addresses this.
The second point introduces some complexity. What is, or should be, “average, business as usual”? More specifically, are people interested in understanding how their building performs when compared compared locally, regionally, nationally, or internationally?
When we started trying to answer this question, some scenarios were very helpful. If a designer wants to compare locally, the benchmark needs to reflect the things that are most important to the overall LCA results. The two most critical things are probably electricity grid and climate zone. Localising just these two inputs gets pretty tricky and the number of possible benchmark permutations starts to add up pretty quickly. In Australia there are four main independent electricity grids (NEM, SWIS, NWIS and Darwin). In the Building Code of Australia there’s 10 climate zones. Accounting for which climate zones occur within each grid, there’s about 20 different benchmarks required. To add to the complexity though, the NEM is split into different states (New South Wales, Victoria, Australian Capital Territory, Queensland, Tasmania and South Australia). Generally, because the National Greenhouse and Energy Reporting guidance splits the NEM into different states, the NEM is usually considered as six different grids. So there’s upwards of 50 different benchmarks we’d need to create and maintain for Australia alone just to localise electricity grids and climate zone.
One disadvantage of this method is it’s still not all-accommodating. It doesn’t account for remote grids of which there are many in Australia. An example is Kunnanurra which is 100% hydro power. So even in this scenario where we had 50 or so benchmarks for Australia, there’s still big potential for a designer patting themselves on the back for a great comparison to the benchmark when really it’s just a local condition, and vice versa. The same can be said about an off grid scenario (effectively just a micro grid of it’s own).
The other disadvantage is maintenance of all these benchmarks. Expanding the above scenario internationally there could easily be 1000’s of possible benchmarks. There’s so many that it would be hard for eTool to initially create them, and even harder to subsequently maintain them. Clearly the localised benchmark option had some big challenges.
At the other end of the benchmarking philosophy we considered just having generic benchmarks, or even one global benchmark. This is perhaps a more user-centric, or building occupant sensitive system. That is, the building occupants are probably more interested in this measure as it’s more about how they live compared to the global community. So a building may be “average” compared to the local context, but actually be very low impact compared to the broader average (due to favourable local conditions). Conceivably, the local conditions contributing to the ease with which a building can perform may be part of people’s motivation for living in a particular area.
The disadvantage of the generic benchmarking approach is that it isn’t as useful for a designer to compare their building’s performance against this as the local conditions (which may create a significant advantage of disadvantage) aren’t considered. This was a big consideration for us, eToolLCD is a design tool, it has to be relevant to designers. Interestingly though, the way eToolLCD is generally used is the base design is modelled, and then improvements are identified against this base design. The benchmark is usually only used towards the end of the process as a communication and marketing tool.
Also, there’s no reason why the designer can’t model their own local benchmark, for example, a code compliant version of their own design.
This topic spurred some serious debate at eTool. In the end, the deciding factors were:
- A local approach couldn’t really be adopted without localising at least the grid and climate zone for each benchmark option. That is, it would have been too difficult to go half way with localisation (for example, only localising climate zone and not grid), as this really just revoked the whole advantage of localising the benchmarks.
- Taking the very localised approach was going to put a huge benchmark creation and maintenance burden on eTool which wasn’t necessarily productive
- The choice of a generic benchmark didn’t detract from the function of eToolLCD as a design tool.
- Greenhouse Gas pollution is a global problem not a local problem, we feel people probably need to measure and improve their performance against a global benchmark rather than a local one.
So the single global benchmark was the direction we choose. Once this decision was made, we needed to determine how to statistically represent global averages. We decided to choose an aspirational mix of countries to make up the global benchmark, that is, select the standard of living that we felt most people in the world aspire to and determine the average environmental impacts of buildings in these demographic locations. This does mean the global benchmarks are generally higher than the actual global average building stock for a given function. That doesn’t stop us from estimating what the sustainable level of GHG savings is against this aspirational benchmark (90%+). It also enables us to strive for this level of savings without adversely effecting our standard of living aspirations (globally). The global benchmark created using this approach is the residential benchmark. More information about how this was conducted can be found here.
For those people or organisations that would like a customised benchmark, eTool can provide this service. Please get in touch.
Going beyond carbon zero.
Archiblox’s latest project is a carbon positive modular home that boasts a difficult to attain eTool Platinum rating. Achieving a platinum rating means the design achieved a 90 per cent overall improvement in CO2e emissions compared to the Australian benchmark along with a minimum of 60 per cent improvement in each category (embodied carbon and operational carbon).
What does it mean to be carbon positive?
A net carbon positive outcome means the building offsets more carbon than it uses in construction and operation throughout the life of the building.
Check out the following press about ArchiBlox’s carbon positive home and if you are in Melbourne, you can check the house out at the Sustainable Festival running until 1 March.
“Australia’s first carbon positive pre-fab home” – SBS News
“Can you compete with a carbon positive prefab home?” – Architecture & Design
“World’s first carbon positive prefab house” – Green Magazine
“World’s first carbon positive prefab house?” – ArchitectureAu
“The World’s First Carbon-Positive prefab house” – Dwell Magazine
Well this is a bit of an odd post as it’s result of me getting carried away in a LinkedIn conversation and blowing the word limit considerably. I’ve ended up posting only the key points on the “linked in” conversation and the detailed response here.
To understand the background please have a look at this conversation (I think you’ll have to sign up to be part of the group) and this blog article. From there you will see where the rest of this following rant comes from.
I think this is pretty massive topic requiring a lot of discussion to get some good outcomes. I’ve ended up with a 50page response as a result.
It also has taken a few tangents which I’ll try to bring back into line with the original topic by breaking it down into four points:
- If you are taking aim at a particular legislation be very clear in your article that is your purpose.
- Don’t be prescriptive in your design approach and push only one strategy (such as passive house) or you’ll get perverse outcomes.
- Don’t write off onsite renewable energy it’s on the increase for some good reasons and is only set to grow even further – embrace it where it works.
- I’ve also gone to address several of your points in detail to provide some more structure to your original article
Those points in detail for those interested enough to read the 50 pages now….
1. If you are taking aim at a particular legislation be very clear in your article that is your purpose.
I was lead to believe it was all about reducing carbon and what targets to set to get there.
I’ll repeat – I’m not across the UK definition of “zero carbon house” and again if your aim was to identify flaws in it then please reword your opening paragraph as well as the bulk to ensure it’s more “explicitly” stated throughout the article. Otherwise it will continue to read as anti onsite renewables, pro passivehouse and not UK specific. This is really dangerous and we will continue to have people around the world blindly following a design strategy that can often result in bad outcomes for the planet.
You have also introduced “comfort targets” into the conversation which I agree is an important element to good design. However if we are targeting CO2e reductions “comfort targets” need to be defined as what is sustainable for 7b people on the planet and not just a lucky few who can live in large “eco” houses. I think this is another topic for another conversation….
If you’re aim in the article was to create some healthy debate then it was spot on 😉
2. Don’t be prescriptive in your design approach and push only one strategy (such as passive house) or you’ll get perverse outcomes.
If reducing CO2e is the goal then CO2e is the only priority when it comes to design strategy. More importantly CO2e should be the basis of your target not “energy efficiency”.
I am totally agnostic in regards to which strategies (be it passivehaus or solar pv) should be prioritised in a project until we have kicked of with Life Cycle Design. Then and only then can you start to see which strategies will provide a genuine reduction in CO2e over the buildings life cycle.
In my home city of Perth we have a Goldilocks climate and very carbon intensive grid which is no where near being destabilised by PV. Unfortunately we still have the vast majority of “eco” designers using all of their clients money to design something that doesn’t need an air-conditioner while having no budget left for solar hot water or solar pv. They’ll reduce their carbon footprint by 10% while the guy down the road in a standard design with solar hot water and solar pv will have a 90% reduction in carbon, lower operating costs and all with less than half the capital cost.
Worse still they’ll chuck large volumes of concrete into the design for thermal mass in the push to achieve the magic “energy efficient” design resulting in an overall increase in life cycle carbon (even with a carbon intensive grid).
If you took the same example up to Kununurra, with a hydro dominated grid, then the solar pv would be a waste of embodied carbon as would the majority of the “radical energy efficiency” strategies. In that circumstance it would all be about the embodied carbon in the materials, transport, construction and maintenance.
Shift it again to various locations in the UK and I bet you’ll find a whole set of new variables and changes in priorities for strategies. Again starting with blanket statements about what should be prioritised without checking each project variables first will result in perverse outcomes.
I know you guys have a much colder climate than we do but I’m still pretty confident that with a proper LCD approach onsite renewables (PV, solar hot water, pellet heater etc) will still come into the mix for a low carbon design.
LCD ensures you apply a rigorous and unbiased approach to each project and provide something that planet and the occupant can be happy with. I would suggest that become familiar with standards such as EN15978 as it will allow you to integrate passivehouse within a much more holistic design philosophy. EN15978 is scientific approach to assessing the environmental performance of a building and is not biased by any existing rating system, design concepts or technology. It’s fast becoming the new benchmark for good design
3. Don’t write off onsite renewable energy it’s on the increase for some good reasons and is only set to grow even further – embrace it where it works.
“It is less costly and more effective to consume radically less energy and emit less CO2 by design, rather than to meet higher energy demand with building mounted ‘Zero-Carbon’ renewable generation.”
Sorry, but this statement is just not true. In some cases the opposite is more accurate. Again horses for courses! I think I addressed this point somewhat above.
Solar PV has dropped in price dramatically and continues to do so. Distributed storage is now doing the same. So if you continue to ignore it or try to push it to the side you will be left behind. Yes it does have it’s challenges as does any developing technology but they are disappearing fast.
I did read that article from Japan and it’s interesting we had a very similar situation in Australia a few years back. In small isolated network there was a really fast uptake in PV and the local utility got scared of stability issues and put a halt on further installations. As a result the industry responded by integrating cost effective distributed storage and away it went again. I’d almost guarantee we’ll see similar responses around the globe not to mention increase in electric vehicles.
Installing PV on roof in Perth can be as cheap as a solar farm ($1-2/Wp). There is already frames (the roof), electrical infrastructure (existing switchboard and meters) and no land costs. More importantly they are off the shelf items without need for expensive engineering, approvals and regulations. As far as this scary maintenance cost the systems I’m familiar with in Perth over 8years old have never skipped a beat. It just comes down to a life cycle cost analysis and trust me it looks pretty good with people taking it up purely on a cost basis with no rebates.
4. Specific points in your original article
“4. ‘Zero-Carbon Buildings’ may increase national CO2 emissions”
Why can’t these buildings also run gas and have the best of both? This is a pretty massive long bow to draw and very misleading to say that it will increase demand on the network.
“In the dark freezing depths of winter, with a gale howling outside, everyone has their heating turned up high and all the lights switched on … and since the sun isn’t shining the photovoltaic systems on the ‘Zero-Carbon Buildings’ aren’t generating electricity. And since the wind is gale force and highly changeable the wind turbines have switched to safety-mode and aren’t generating electricity!”
Wow, this is sounding like some of the anti renewable energy climate change skeptics. Again can’t the house have both renewables and gas? Furthermore distributed storage is on the way and on the way fast. If you don’t think so then have a think about the people who said mobile phones would never get past one per 200 people.
Houses with onsite renewable energy somehow increase the demand on the network even in hot climates?? Well I can tell you from personal experience in Perth we saw the government build another $300m power station to deal with this peak only to find that solar pv cut the peak dramatically and they never turned it on. Again you need to ensure you’re treating each project on it’s merits and not casting blanket statements or you’ll get tripped up.
8.‘Zero-Carbon Buildings’ is an abstract and unreliable idea
Sorry this is totally incorrect and also damaging to the progress we are making in getting people to think about CO2e. EN15978 lays it out pretty simply. Run a Life Cycle Assessment and you’ll have a much more reliable picture of reducing CO2e in a building.
Energy is not CO2e much like food cost is not measured in volume of food. Saying the only way to reduce CO2e in a house is to focus on radical energy efficiency is like saying we are going to cut our weekly food bill by eating less volume. So off you go to the shops and buy cheese wine and caviar and cut out the bread, rice and fruit (too much volume), furthermore you stop eating the produce from your own veggie garden. Somehow your food cost went up?
Many forms of energy have really low carbon intensities, some you can grow at home with very small carbon intensities and sometimes investing large amounts in energy efficiency can increase your carbon emissions.
Please explain how tackling CO2e by looking at energy and not CO2e be can less abstract than just targeting the CO2e in first place?
To wrap it up in conclusion this whole article first up appeared to be about reducing CO2e associated with houses. If this is the goal (which it should be) then setting a “zero carbon” target is exactly what we need to do. Simple….
Fei Ngeow, eTool LCD Engineer, recently attended the 2014 EBAA Conference: ‘Earth Building – Towards Zero Carbon’, in NSW. The two-day conference was held the the Bamarang Bush retreat in buildings constructed with mud brick and included workshops and guest speakers on varying topics related to earth buildings.
Life Cycle Performance Comparison
External Wall Comparison
Life cycle analysis shows that a 250mm mud brick wall has a 95% improvement in embodied CO2 over a 110mm rendered brick veneer wall.
- Mud brick wall – 250mm puddled mud brick wall made onsite, finished with 10mm clay/bitumen render.
- Brick veneer wall – 110 brick, insulation, plasterboard paint internal finish, render external finish.
Embodied Energy Comparison
Embodied & Operational Comparison
- reverse cycle heat pump (CoP = 3.65, EER = 3.4)
- 85% efficient gas HWS
- CFL lighting
- gas cooking
The house comparisons have been modeled in a cold climate zone (Tomerong) and therefore have a minimal cooling requirement and high heating requirement. When low carbon alternative heating solutions such as wood pellet heaters are incorporated, the embodied emissions make up a larger proportion of the total.
Although the mud brick still requires more heating, because the heating source is very low in emissions in both cases the total operational energy decreases meaning, the embodied emissions proportionally increase. The relative savings from the mud brick walls then become more significant. If houses can be designed optimally, to minimise cooling requirements, low carbon outcomes are easier to achieve through the use of renewable heat sources.
The grid emissions in the above two scenarios are assumed constant throughout the life cycle of the building. In reality the grid emissions will decarbonise if Australia is to meet its commitments to Kyoto (80% reduction in CO2 by 2050). Again the embodied emissions become more significant because the operational makes up a smaller proportion of the overall emissions.
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