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Zero carbon is today’s buzzword. But does the term itself help us achieve the lowest carbon emissions possible from our buildings? According to Jess Hrivnak, Hero Bennett, Rich Spens and David Robinson from Max Fordham’s Sustainability Team we should be moving forward regardless of how we define it.
So what does the term “zero carbon” actually mean?
After four years of endless discussion and debate, we have had more explanations to that question than solutions to the subject. What passes as zero carbon is sometimes so blurry, it is hard to recognise.
In 2007 the then-Labour government declared a zero carbon target for new dwellings and new non-domestic buildings. In one notable incident it was even said to be a “moral duty” to deliver zero carbon. The understanding was that these homes would need to emit zero carbon from both building systems (heating, hot water and lighting) and household appliances (TVs, kettles, hairdryers etc). They had to achieve the energy performance of a Code for Sustainable Homes Level 6 house.
That original definition, although difficult to achieve, proved aspirational. It loomed over the building industry, forcing its hand. It pushed designers to find creative and innovative carbon reduction solutions. However, it proved extremely difficult to achieve in most cases, primarily because the definition excluded off-site renewables not connected by a direct private wire. House builders and others in the industry raised concerns that this definition was unworkable and costly.
In response, the “allowable solutions” concept was introduced in mid-2008. It aimed to remove the barrier of the “direct wire only” renewable solution. Zero carbon developments would now be allowed to count certain off-site interventions in their carbon emissions calculations. Now the discussion and debate surrounded what offset solutions would be allowed in allowable solutions – everything from additional renewable energy provision to insulating neighbourhood properties was thrown in the ring.
In December 2010 the Zero Carbon Hub put forward recommendations to the government on not only what you were allowed to offset through an allowable solution, but also of carbon compliance – what you need to achieve on-site before resorting to allowable solutions.
These recommendations sought to make the aspirational zero carbon target, and our “moral duty”, workable. They were not intended to be a cure-all solution – it would still be challenging to deliver, especially within the UK’s stressed economy.
In March 2011, with a recession and a change in governance, the shock post-Budget response to the fiscal and technical challenges was to remove household appliance energy use (unregulated energy) from the zero carbon definition. This makes Code for Sustainable Homes Level 5 the new zero carbon.
So, what do we call the Code for Sustainable Homes Level 6 now – zero carbon plus? Is it possible to improve on “zero”?
It may be a tongue-in-cheek philosophical question, but a pertinent one. Deciding a definition has been rife with changes and confusion, which may weaken the support for sustainable action and stifle growth in the sector.
So while striving for conciseness is clearly a good thing, the hunt for a definitive definition continues to distract from the real issue – how do we actually go about creating buildings that use less energy and therefore emit less carbon?
It is true that the two have to happen in parallel, as painful as that process may be. But getting consensus on the term as well as getting the definition to reflect the original aspiration is vital if we want to avoid downgrading our ideals to a green-wash.
Everyone needs to take responsibility for pursuing the aspirational target and not get side-tracked trying to define it.
Building basics
Building regulations provide the minimum standards for assessing regulated energy use in building design and construction. It is the least we must do. By continually improving building regulations to reflect best practice, they help to encourage more innovative and pioneering solutions.
However, it is going to take more than just building regulations to meet our carbon reduction commitments for 2050. Like the Code for Sustainable Homes or BREEAM, it is a static measure and does not measure the building’s actual energy performance in use.
As part of a Knowledge Transfer Partnership at Max Fordham, we looked at the designed and actual energy performance in 15 schools and found that, on average, they used 40% more energy than their design prediction. Operational energy is notoriously difficult to model due to the “human factor”. As building designers, we cannot forget that we are creating dwellings for real people who use electricity through televisions, computers and other appliances, and not always when we expect them to.
Building designers and consultants need to focus more on learning how our buildings are being used, so we can better predict how our designs may be used once built. We should not absolve responsibility for unregulated use and just brush the problem under the carpet. This would not challenge us to gain a better understanding of the real carbon costs of working or living within the buildings we design.
Add to that the knock on effect of discounting unregulated energy use. The quantum of installed renewables will reduce if unregulated loads are taken out of the equation. Planning requirements to reduce emissions by a fixed amount will be satisfied with less actual installed renewables. If the budget is already tight, there is little reason to deliver more.
The building industry needs to think beyond building regulations, considering post-occupancy support to educate users. Ultimately, designers and consultants need to take responsibility for guiding the client and the users through all the carbon-saving possibilities, making sure they understand how it is designed to work so they can do it themselves.
Re-energising energy lessons
Government policy has come a long way, but there is still further to go. Planning policy plays a massive role in shaping sustainable communities.
As designers it is our role to create the buildings that form these communities. However, our influence stops at the front door. The number of televisions a home occupier installs is beyond our control.
But it is not just up to the consumers to make the choice to turn off their appliances – it is up to manufacturers to design goods that encourage people to use them efficiently. All of us should be pushing manufacturers to design with carbon savings in mind. Stand-by settings should not be a discreet orange light, but an irritating flashing light to tell us we are still using energy and get us to turn off the plug.
Just like with building regulations, best practice needs to be the norm. Technology needs to allow energy efficient behaviour as standard, not an additional measure. A “normal wash” should be a cold setting, so we’ll only choose a hotter wash when we need it.
Once more efficient systems are used it is important to manage the resulting misconceptions. Just because we have saved energy does not mean we now have free energy brownie points to use later on. That is Jevon’s Paradox – in the short term, energy use is reduced, but long term people start using more energy in other ways. And perhaps the hardest thing is that we shouldn’t keep buying more “efficient” gadgets that we do not necessarily need. We need energy savings to stay savings.
So we should be encouraging people to install renewables on their roof, but we need to squash the view that because they have done that, they can buy three more televisions or turn their heating set point back up. It does not make heat, electricity or any energy free. There is always a cost.
Maintaining Momentum
It is clear we have got a long way to go before reaching true zero carbon.
But we need to remember, even if we cannot achieve an aspirational target, it still provides a clear driver. It pushes the industry closer towards the goal.
Defining the term has become a distraction to the real aim. After all, it depends on the reader as to how the term is perceived – it may help or hinder the actual mission. Aspirational targets can be motivating for the converted, but demotivating for others who see the problem as too big to handle.
And when we break down the problem, we all have parts to play. If we all take responsibility, we can step ever closer to a zero carbon future. The how-to concepts certainly are not new and they are not hard to understand. It is just getting them done that is tough.
Community Thinking
To many, allowable solutions may seem like a developer’s easy way out. But as the Zero Carbon Hub confirmed in their work on Carbon Compliance, sometimes there is a limit to what can be achieved on-site. So should we not see allowable solutions as an opportunity?
Joined up thinking about allowable solutions allows us to act beyond the site boundary, investing money in tangible carbon savings that have wider benefits. For example, retrofitting existing homes in the site’s neighbourhood to reduce their own carbon emissions benefits local residents in a real way. Bulk procurement opportunities will be able to deliver fabric uplift more economically than perhaps residents alone could. Such neighbourhood energy efficiency proposals could go some way to assist in mitigating fuel poverty for those not able to undertake the work themselves. Creating Community Energy Funds should also enable local people to install renewables to benefit their entire community. But overall, allowable solutions offer opportunities for best practice masterplanning strategies, which local authorities should demand when developing local plans. Together, local authorities and developers might find solutions that would otherwise not have been possible.
Case study: tackling existing housing stock with the ‘Retrofit for the Future’ program
There are around 26 million existing homes in the UK, and it is expected that 85% of them will still be in existence in 2050. So, reducing the carbon emissions of the existing housing stock will be an important part of the zero carbon story. The Existing Homes Alliance estimates that 500,000 whole house refurbishments will be necessary each year to 2050. So what does it take to achieve zero carbon in an existing home?
The Retrofit for the Future programme was initiated by the Technology Strategy Board to answer those questions. It set an 80% carbon reduction target, which is required nationwide by 2050 in the Climate Change Act. As part of the programme, we worked with Peabody, Feilden Clegg Bradley Studios and Wates to perform major retrofit on a Victorian terraced house in Wandsworth, London. Interventions included significantly improved fabric, new heating plant and controls, continuous extract ventilation with heat recovery to hot water and solar thermal panels.
During the design stage we elected to omit the PV array to provide cost savings to safeguard other more innovative features such as the low power exhaust air heat pump. If the PV contribution were taken into account, the carbon reduction target is expected to be achieved – but at a prohibitively high cost. Results from across the programme show that a 60% reduction is more realistically affordable – costing approximately half of what it costs to retrofit to an 80% reduction (see graph above).
A 60% reduction is a more realistic target for the national programme, with the remainder achieved by decarbonising the grid.
Case study: striving for zero carbon at Ivy Farm
The Ivy Farm project is a unique new build family home for a fruit farmer in an orchard setting. The design achieves the tough Code for Sustainable Homes Level 6 energy target – the first zero carbon definition – with zero carbon energy emissions annually for the building and household.
Code for Sustainable Homes Level 5 would have been achieved with passive design and photovoltaics; however, the client chose to strive for the higher CfSH Level 6 standard, which includes unregulated loads, effectively doubling their target for renewable energy.
In this case, the tough target drove us to take an innovative approach. The design now uses the developing technology of anaerobic digestion to convert the farmer’s copious fruit waste to provide its electricity and heat otherwise excluded from the CfSH emissions calculations as shown in the graph.
The definition decline
Up to Mid 2008
All carbon emissions to be mitigated on site. (Code For Sustainable Homes Level 6). Essentially zero carbon achieved using energy efficiency and on site low and zero carbon technologies.
Mid 2008
Concept of Allowable Solutions proposed after studies revealed that it would be impractical to achieve zero carbon on many sites using the Code 6 definition.
No attempt yet to specify scope Allowable Solutions.
Mid to late 2009
A 70% Carbon Compliance line is drawn by Government after initial consultation (note that this 70% reduction of emissions applies only to Regulated Energy use), leaving Allowable Solutions as the mechanism for mitigating about half of the carbon emissions from a typical home. In late 2009, a minimum Fabric Energy Efficiency Standard is proposed as part of Carbon Compliance.
February 2011
Evidence-based recommendations identify more realistic Carbon Compliance levels for homes: approximately 60, 56 and 44% reduction over 2006 levels, depending on dwelling type. Allowable Solutions now required to mitigate significantly more than half of the emissions from a home Carbon Compliance is to be based on actual performance.
March 2011
Post Budget, the emissions from unregulated energy use are no longer in definition of zero carbon. Allowable Solutions are still needed, however, to bridge the gap between the Carbon Compliance levels proposed for 2016 Part L and the zero carbon target (now defined as ‘no emissions from Regulated energy use’).
The decline of the zero carbon definition, as published in a report by the Zero Carbon Hub, shows the current model which disregards unregulated energy – sweeping a considerable portion of our energy consumption under the carpet. The unregulated figures are also based on a modelled value, meaning that in reality the missing tip of the triangle could be much bigger.
The true effect of energy use
“Percentage change in carbon emissions due to variations in key input factors” from Max Fordham’s Energy Performance of Schools report.
Thanks to a government drive to deliver hard carbon reduction results, Max Fordham undertook a KTP research project with the Bartlett School at UCL to understand and manage the discrepancy between carbon emission predictions and actual energy usage of new buildings. We focused on the education sector, examining the energy performance of 15 schools, identifying what aspects of the buildings use and management has the biggest impact on energy performance - and finding the areas not controlled by building regulations can have more effect than those that are.
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