NEUTRAL IS POSITIVE – CARBON NEUTRAL, BACK ON THE AGENDA By Darren Evans, Managing Director, Darren Evans Assessments


Earlier this year the government scrapped its zero carbon homes plan – again. Were the plans too ambitious or were they just simply not required or valued by the industry? Many believe it was the wrong decision. But the question remains, are zero carbon or carbon neutral buildings financially achievable in the current climate and does the desire still exist to strive to create them?

In May of this year the government overruled the House of Lords and scrapped the zero-carbon homes policy – a policy it had scrapped in July 2015. The House of Lords had attempted to reinstate the standard for all new homes through an amendment to the Housing and Planning Bill but the proposals were thrown out. Instead, the government committed to a review of energy standards in current Building Regulations. To many, including the UK Green Building Council (UKGBC), this is seen as a very ‘weak clause’.

The abandoned zero-carbon rules, which were due to come into force this year, would have required new housing developments to generate energy through renewable sources such as solar panels or ground-source heat pumps. So why the u-turn and where does that leave our drive for lower energy homes?

One reason given for the scrapping of the regulations was to boost housebuilding. This seems a contraction given the fact that in July, two months after scrapping zero carbon homes, Housing minister, Gavin Barwell, said that the Government remains committed to building 1 million new homes.

So whilst we are getting mixed messages from Government and a lack of legislation to drive the carbon neutral agenda, how does the market view our position? Is there a place for zero carbon homes?

Sustainability is now considered a norm. However all too often motives for sustainability, especially in the commercial sector, are short term and driven by motives such as quick financial gain. For example, carbon reduction with the driving force being reducing immediate energy costs rather than long term resource efficiency. In the housing sector, whilst there is no doubt that housebuilders are ‘making hay whilst the sun shines’, there are more discerning clients, especially housing associations, looking at the future and realising that the great gains are made by playing the long game.

You only have to look at the growth of BREEAM the internationally recognised measure of sustainability for buildings and communities. More than 530,000 certificates have been issued under BREEAM on more than 24,000 projects in over 70 countries and over 2.2 million buildings and communities are registered for certification. This has to be the largest, global, indicator that developers, tenants and clients see the value in sustainability.

Whilst achieving zero carbon isn’t easy and it can come at a cost, many are now understanding the long term gains. It is estimated that a mixed-use development built to BREEAM Outstanding will add around 4.8% to the overall capital costs. However the payback in terms of lower running costs can be less than 10 years. Long game? 10 years isn’t that long!

The growth in the application of passive techniques in the UK and the reduction in cost of renewables are now making zero carbon a commercial viability. Yes there is still work to do to educate homeowners what living in a zero carbon homes means and the lifestyle changes required. However at a time when consumers are looking at how they can save themselves money, present someone with an opportunity for low or even zero utilities bills and they will bite your arm off.

I am pleased to see more clients looking forwards and talking about how they can achieve carbon neutral developments. We need to make sure that zero carbon is seen as a long term positive and like sustainability, becomes a norm rather than a aspiration.


WELL, WELL, WELL By Darren Evans, Managing Director, Darren Evans Assessments

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Sustainability has been at the top of the agenda for many years but I have an ever-increasing feeling that much of the industry is missing the next step. Over recent years we have been placing our emphasis on the environmental and economic parts of sustainability, but we shouldn’t forget the fact that we are creating buildings for people and the well-being of these people should be the priority. So the question is: Are we putting buildings before people? Is it now time to place greater emphasis on people?

When you look at costs in relation to buildings, we freely talk about energy savings but our biggest cost is the people within them and this figure is an astonishing 90% of that overall cost. In addition it has been claimed that we spend over 90% of our time indoors and in an office environment. So why has the focus been put firmly on creating better buildings when, in fact, we should be creating buildings to make the occupants feel better, and in turn, happier and more productive? Imagine what we could achieve if we were able to increase productivity in an office by just 1% simply through creating a better working environment? Well, I have a feeling this is all about to change.

A couple of months ago it was alluded to in an article in Building magazine that the WELL Building Standard could soon be aligned with global sustainability standard BREEAM. The WELL Standard, created by US-based consultants Delos, measures human health and wellness using evidence-based medical and scientific research to help inform better design of buildings. To quote Delos founder Paul Scialla and Building magazine: “Delos are in talks with BRE about pairing the WELL Standard with BREEAM.” This could be a major step forward to aligning the performance of buildings with the wellness of its occupants as reinforced by Scialla who stated that he realised 7 years ago there was a “huge gap in regard to not enough understanding of how the built environment really is impacting biological sustainability as opposed to just environmental.”

BREEAM has long been the ‘go to’ standard to help deliver sustainable buildings. Used in more than 70 countries and with 24,000 projects around the world, and more than 2.2 million buildings and communities registered for certification, it is clear to understand the value that the built environment places on BREEAM. Whilst BREEAM does encourage occupier and building owners to continually monitor performance, it doesn’t go as far as looking and measuring occupier behaviours and well-being. Surely this is the next natural step? And, as if on cue, we have WELL.

Whilst the WELL Standard has been in existence for some years now – most actively in the USA – it is relatively new to Europe. However, Studio Ben Allen Architects’ One Carter Lane project is on course to receive the accreditation. One Carter Lane, the new London headquarters of engineers Cundall, is a 15,400ft² Cat-A office fit-out. The fit-out provides new workspaces for up to 180 employees and attained a BREEAM Excellent rating and SKA Gold certification.

The WELL Building Standard defines a set of compliance requirements that cover seven key areas: air, water, nourishment, light, fitness, comfort and mind. It looks at driving change towards more personal criteria such as stating that 30% of staff must have space to eat lunch together; materials such as desks and storage must use natural materials; and that the volatile organic compound (VOC) rating of all materials must be between negligible and zero, thus ensuring that office fixtures, fittings and fabric do not expel harmful chemical or organic emissions.

So how does all this help to improve well-being and, whilst we can measure productivity, how do we actually measure emotions such as happiness and the direct effect this has on outputs? And the big question is: What cost does this add to a project? According to Cundall it has added around 3% to the project value which equates to just £200 per head.

There are elements of WELL that will need to be addressed if it is to become mainstream in the UK, in much the same way that BREEAM has. For example, in the UK and many other European countries, certain standards are higher than those within WELL. A comparative base line will need to be created so we are not rewarding for going backwards. Also the business case will be different. In the US there is no NHS, instead private healthcare is provided by employers. As such there is a clear reason for US employers to adopt WELL to increase productivity and reduce their healthcare costs. We may need to look at incentives for UK employers.

In the case of the success of One Carter Lane, time will tell, but the initial reports do indicate that a working environment that promotes happiness, well-being, positivity and improved productivity has been created. The challenge is how do we adopt wellness in the same way that we have embraced sustainability?

For me, wellbeing is a vital part of every building – whether it is a school, a hospital, an office or a home. Buildings that make us feel comfortable, happy and calm are essential. With so much of our time spent indoors, and with illness costing UK businesses on average £550 per employee per year (a total of about £30bn, according to the Chartered Institute of Professional Development) it’s something that we all need to embrace – after all we build buildings for people.

WHAT PLACE DO STUDENT PLACEMENTS HAVE IN OUR INDUSTRY? By Jack Roberts, Trainee Sustainability Assessor at Darren Evans Assessments

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The last few months have shown that we live in a rapidly changing society and we are entering the great unknown when it comes to our relationship with Europe. As a student, there are many decisions to make when it comes to choosing a career. With so much uncertainty is the construction industry still a sure bet for a lifelong career?

At its pre-recession peak in 2008, the UK’s construction workforce was over 2.58 million, by the end of last year this had dropped by nearly 13% to 2.25 million. This shift, during the recession, has caused a skills gap, within the industry. As such, it would seem that this very large industry still has a lot to offer graduates.

I’m studying BSc Environmental Resource Management at the University of West England in Bristol. Before my final year of study I wanted to gain practical experience from the industry to help me complete my final year project as well as giving me a head start with a future career path. I’m soon to complete a 13 month industrial placement at sustainability consultants; Darren Evans Assessments.

My role as a Trainee Sustainability Assessor has involved working on residential projects ranging from; multi-residential retirement villages, sites of over 100 dwellings to a single private house project. Work has focussed on both the Code for Sustainable Homes (CfSH) assessments, ranging from entry level above building regulations to zero carbon as well as, SAP calculation to comply with Building Regulations Part L.

When looking for a placement opportunity I was very open minded about what role to go for. I had minimal construction knowledge – my parents once built a house about 7 years ago, that was about it. However, the industry has always had an appeal – I have always been interested in new houses or developments being constructed nearby. With this in mind, I looked upon my placement as an opportunity to develop skills and experience in a sector I knew little about but where I knew the skills I would learn could be transferrable.

My placement has made me change my perception of the industry considerably. I find it fascinating and I love learning about new developments and really enjoy being a part of a team working on these schemes.

The importance of practical ‘hands on’ experience is vital. The placement has made me realise the challenge of learning academic material at University but then finding that the real life application is very different – the skills you learn in the classroom provide you with a good background to certain processes but their real life implementation is very different and in many cases, coursework doesn’t equip you with the knowledge to apply your learning. For example, I knew the basis of SAP calculations and that on completion they produce an EPC. However I didn’t know how they were carried out. Since finding out how to do this first hand, I have also been able to share this knowledge with some of my fellow students as well as my lecturers.

So, if we combine the challenge of the skills gap with the fact that graduates are going out into the workplace who have academic skills and understanding but not the practical skills to put them into place, it does question why our Colleges and Universities do not have a better relationship with the industry. It highlights the fact that placements are a vital part of a degree, providing the link between academia and the real world and allowing students to align their learnings with application.

I would love to come back to Darren Evans Assessments upon graduation to develop my knowledge of the industry or alternatively work for a major housebuilder, where I can make suggestions on improving their building efficiency using the knowledge I have gained from my placement, as well as my degree.

Whichever route I choose I know that the decision to include a placement within the construction industry has put me on a path to an exciting career in, what is undoubtedly, one of the most exciting industries in this country and possibly the world.

HOW TO ACHIEVE A GOOD U-VALUE Sophie Peters, Sustainability Assessor, Darren Evans Assessments

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U-values (measured in Watts per metre Kelvin – W/m2K) measure the rate of heat loss through building elements. As they impact on both the dwelling emission rate and fabric energy efficiency targets, they ultimately govern the result of the SAP (the Standard Assessment Procedure) test used to assess a house’s energy performance. Achieving ‘good’ (low) U-values gives you the baseline for achieving and exceeding Building Regulations. But what are the best ways to achieve a good U-value? There are so many options in terms of design and materials you can be spoilt for choice. So where should you start?

To know what may be deemed as a good U-value it is important to know how it compares to the U-values in the notional building used within SAP for Building Regulations compliance. The notional U-values within Part L Approved Document L1A 2013 are as follows: – external walls 0.18 W/m2K; party walls 0; floors 0.13 W/m2K; roofs 0.13 W/m2K; windows 1.4 W/m2K and opaque 1 W/m2K.

Achieving U-values higher than these will go against you, having a negative impact on the SAP and making it more difficult to pass.

There are a multitude of methods and construction types you can use to achieve good U-values however. Each product will differ slightly from the next, meaning that expert advice in tweaking product selections can help towards generating the best overall U-value.

There are also limitations and constraints which vary between projects. For example, lightweight aircrete blocks have improved thermal efficiency compared to a standard concrete block. However, it is not appropriate to use them for some designs due to their compressive strength.

The most important building element to focus on in achieving low U-values is the external wall element (masonry construction) as being a large exposed area it is often the cause of an SAP failure. From recent experience on projects, most contractors look to keep the overall wall thickness to 300mm, with cavities then either partially or fully filled using mineral wool or PIR insulation. A high performance full fill PIR would be sufficient to achieve a U-value of 0.18 to match the notional dwelling without requiring any internal insulation or increase in size of the cavity. (Maintaining the cavity at 100mm is desirable to avoid impacting the plot size and altering the requirement of other products, such as lintels and wall ties.) In this scenario, an aerated block would need to be used for the internal leaf; its specified thermal conductivity depending on what performance is required from the insulation in order to meet the target U-value.

Example 1: Full fill cavity wall, 0.18 W/m2K

This example of a U-value wall offering notional building U-value would internally comprise a 3mm plaster skim, 12.5mm plasterboard (lambda 0.21), 15mm minimum plaster dabs cavity with the following masonry, cavity insulation and external elements: – 100mm Aircrete block (lambda 0.15); 97mm Celotex CG5000 PIR insulation (lambda 0.021); 3mm cavity; medium density concrete block (lambda 0.57) and render.

In some areas, due to over exposure to driving rain, it may not be suitable to use full fill insulation, with a larger residual cavity being required to prevent moisture infiltration, plus foil backed PIR insulation which will offer high performance within the cavity. If a glass mineral wool product is used, offering much lower thermal performance than PIR insulation, the wall would need to be further insulated internally to meet the target U-value (this is also the case with full fill). To be able to achieve 0.18 W/m2K with a partially filled cavity wall, it is necessary to increase the cavity size or use insulated plasterboard on the internal wall.

Example 2: Partial fill cavity wall for 0.18 W/m2K (100mm cavity)

This would internally comprise 3mm plaster skim, 12.5mm plasterboard and 25mm Celotex PL4000 PIR insulation (offering 0.022 U-value) plus 15mm minimum plaster dabs cavity. Masonry, cavity insulation and external elements would include: – 100mm Aircrete block (lambda 0.15); 50mm Celotex CG5000 PIR insulation (0.021); 50mm Low-E cavity; medium density concrete block (lambda 0.57) and render.

Example 3: Partial fill cavity wall for 0.18 W/m2K (150mm cavity)

This would comprise of internally, a 3mm plaster skim plus 12.5mm plasterboard and 25mm Celotex PL4000 PIR insulation (0.022). Masonry, cavity insulation and external elements would include:- 100mm Aircrete block (lambda 0.15); 100mm Celotex CG5000 PIR insulation (0.021); 50mm Low-E cavity; medium density concrete block (lambda 0.57) and render.

If you are looking to provide U-values lower than the notional building specification for your overall construction, you need to be prepared to make improvements elsewhere further to those to external walls in order to pass the SAP calculation.

HOME QUALITY MARK HERALDS NEW ERA OF QUALITY IN HOUSEBUILDING – BUT IT’S A WORK IN PROGRESS – Ben Wallbridge, Energy & Sustainability Assessor, Darren Evans Assessments


The Home Quality Mark (HQM) has now officially joined the highly successful BREEAM family of quality and sustainability standards, stepping into the shoes of the now defunct Code for Sustainable Homes as a voluntary national housebuilding rating scheme which pretty much covers all of the bases. This comprehensive new standard incorporates elements of BREEAM and the Code but in its nascent and still developing form how workable is it?

The scheme was soft launched as a beta version last October which is a fully functioning standard but with the industry being actively encouraged by BRE to feedback from their experience of using it in practice to help hone the final version. This very open developmental approach is welcome however it does mean that the Mark as it stands is still something of a work in progress.

Developing a simple star system which makes sense to the two key audiences of consumers and housebuilders is laudable, but behind the ratings are a complex matrix of criteria for gaining credits which go way beyond the building itself to provide wide-ranging detail on a house’s credentials. These range from wellbeing issues such as air quality, transport and amenities to resilience, energy costs and post-construction fabric testing.

The layout and methodology of the HQM Technical Manual will feel familiar to assessors who have worked with the CfSH or BREEAM but seems even more intuitive and informative with three overarching sections: ‘Our surroundings’, ‘My home’ and ‘Knowledge Sharing’. For each there are indicators graphically represented with their importance in the scheme and the credits awarded – the indicators being cost, health & wellbeing and environmental footprint. These feed into the final certificate which informs the end user about their home.

Numerous study sites have been initiated by BRE which are informing the technical and operational feedback into the scheme although the number of HQM registered sites under the beta launch has not been released. The fact that registrations are free for six months should help encourage forward-thinking developers and clients to get involved.

Although the beta version of HQM is a fully functioning scheme, the BRE are welcoming feedback on all levels. While it is unlikely that the fundamental mechanisms and layout of the scheme will change drastically, it’s possible the first non-beta edition of the Technical Manual will have slight differences in terms of elements such as credit weightings, evidence requirements, or section wordings.

The initiative was launched nearly a year ago at EcoBuild 2015 and will have a strong presence at Ecobuild 2016 including sponsoring the first day of the event which focuses on housing. This will keep the new scheme in the forefront of the industry’s mind and help everyone to become more familiar and more knowledgeable about HQM going forward.

At HQM’s launch at last year’s Ecobuild Tony Barton, Executive Chair of consultant Sustainable Homes proclaimed that he “expected it to fly off the shelves, because we know the demand is there.” It may take time for it to usher in a new era of quality in housebuilding with builders using a star rating as a differentiator in the marketplace and housebuyers benefitting from an independent guarantee that their new home is not only well designed and built, cheaper to run, healthier and more sustainable. It is an exciting initiative with a lot of potential but with only 59 assessors currently qualified to use it in practice, it is a case of watch this space.

CLEARING UP CONFUSION AROUND THE CRITERION 3 CHECK ON SUMMER HEAT GAIN Marcus Eves, Sustainability Consultant, Darren Evans Assessments

DEA blog - sunSummer overheating has been a hot topic in recent months, however the Building Regulations do make provision for limiting the effects of solar gain. Unfortunately despite being a requirement for compliance with Part L2A of the Building Regulations, the importance of the Criterion 3 check on how much buildings are being heated via windows is often overlooked and misunderstood.

Whilst we are all familiar with the requirements of Criterion 1 (Compliance with the Building Emission Rate), Criterion 3 (Limiting the Effects of Solar Gains in Summer) always seems to get forgotten about. And when it comes to finding a route to achieving compliance it can leave some confused and frustrated.

In commercial buildings compliance with the emissions targets is straightforward, proceeding through the reliable time-honoured menu; lower the U-values, improve the building services, enhance the controls and finally consider renewables. However many are unfamiliar with how the Criterion 3 check is performed in SBEM (the BRE’s Simplified Building Energy Model for non-domestic buildings). When it comes to compliance the implications of this can be drastic.

For the purposes of Part L, a ‘limiting solar gain check’ is performed for Criterion 3 compliance where the aggregated solar gains between April and September must be below a certain benchmark. It is crucial to understand that this does not mean a straightforward overheating check is carried out and is related to solar gain via windows only. Provisions must be taken to limit internal temperature rise due to solar gain in summer; this will reduce or eliminate the need for air conditioning or mechanical ventilation which will increase the building’s energy demand.

In Part L 2006 the Criterion 3 check carried out in the SBEM was based on overheating assessment and therefore any zones which were mechanically cooled were exempt. This gave a quick fix to developers: if a zone failed Criterion 3, a cooling system was added and a pass could be demonstrated. This is not the case anymore. Mechanical plant cannot simply be introduced to offset an issue as a result of poor façade design.

Consideration needs to be given to the design of the building very early on to limit solar gains entering the spaces. There are three main factors to consider:

  • window size and orientation;
  • solar protection through internal or external shading or improved glass specification;
  • high thermal capacity.

When the Criterion 3 limit is exceeded by a small amount – up to 30% – consider the glazing specification and blinds. Windows with lower G-values will restrict the amount of solar radiation entering the space. Blinds will also have the same effect, but these are not appropriate for all spaces.

When the Criterion 3 limit is exceeded by a larger amount (up to 50%) consideration must be given to the glazed area proposed. A reduction in the number of openings or their size may be required. If curtain walling is proposed, spandrel panels can be introduced to reduce the area of glass but keep the overall feel of the building.

Finally external shading must be considered; such as the introduction of overhangs to windows, vertical or horizontal fins, or brise soleil. This will have significant impact on the building form and so will require resubmissions to planning, therefore it’s vital the impact of Criterion 3 compliance is identified at the earliest stage.

It must be noted that if external shading is required, SBEM does not take this fully into account. A full overheating study using a bespoke Dynamic Simulation Model will be required in order to demonstrate to building control that the internal comfort conditions will be met.

In summary, recognising that compliance Criterion 3 is restricted to solar gain from windows, it is important to also acknowledge there is a trade-off between maximising the benefit of daylight and limiting solar gains. Also it is essential to recognise the impact of Criterion 3 compliance prior to planning submission and that the introduction of building services such as air conditioning or mechanical ventilation are not a fix. Lastly, achieving compliance can be expensive and in some instances affect a building’s form.


AN ASSESSMENT OF THE YEAR – Darren Evans, Managing Director, Darren Evans Assessments

year in review2015 has flown by but as we look back at the year a lot has happened externally in the industry both good and bad while we have seen to see a continuing stream of clients seeking sustainability-based building assessments. A somewhat nervous start to the year with the industry wondering what sort of Government would emerge from the Election saw a slowdown in housebuilding but this was balanced with a rise in commercial activity – which we bore witness to working on a number of new projects.

Although Help to Buy was helping to sustain consumer confidence, tighter regulations on mortgage lending kept housebuyers subdued in the lead-up to the Conservatives’ win in May. However the sector has started to pick up since the summer, bolstered further commitments from Government to build 400,000 homes by 2020 including 200,000 starter homes, backed by a hefty £2.3bn to help developers build them.

Housing Associations on the other hand remain worried, as the Government continues on its path to extend Right to Buy for more social housing tenants, which reduces HAs’ ability to build based on the traditional model of borrowing against projected rental income. However in more positive news towards the latter half of the year, the London housing and economic ‘bubble’ which had been holding the market up began to spread across the UK during the year, with other major urban areas seeing positive figures on housebuilding.

It has to be said that 2015 will be remembered in the sustainability community as the year the Zero Carbon Homes project died, with the Government deciding to cull the 2016 target post-Election, which would have given housebuilders one less hurdle to jump through. The ending of Green Deal funding from Government was probably less of a shock, but we remain interested to see what the BRE’s Peter Bonfield will come up with as an alternative following his major consumer-focused review of Government energy efficiency policies which is due to report early in 2016. From what we hear he has taken the fairly clever step of putting the ball back in the industry’s court to develop appropriate schemes, rather than wait for a top-down approach from Government, as that isn’t likely to happen.

Talking of the BRE, we celebrated the 25th birthday of BREEAM in 2015 within our regular series of blogs, realising that the world-beating sustainability assessment tool is now being used in an amazing 72 countries to bring teams together and achieve better buildings. We are glad to see it continuing to fire on all cylinders and evolve over time, as a key weapon in our armoury as assessors. Part of the industry-driven quality improvement that we may see in 2016 may come from the Home Quality Mark, which is an important offshoot of BREEAM hoped by BRE to replace the Code for Sustainable Homes and incentivise consumers as well as housebuilders to demand better houses across a huge range of criteria. This star-rating stamp of quality has yet to fully emerge but it should be one to watch in 2016.

From a staff prospective, we have had a productive and fun year, with one member of staff giving birth to a baby boy, staff members triumphing in our company karting race, and raising over £4,000 for charities from including Children With Cancer. We also had two more staff certified as BREEAM Assessors, taking our team delivering BREEAM assessments to a total of four.

Over the year our blog posts have covered a variety of topics relevant to the positive impact of sustainability in construction, from the growth of district heating and what that means for UK towns, to what needs to be done to ensure responsible timber sourcing. We look forward to bringing you more topical and interesting blogs in 2016, and with the UK signing up with the rest to the binding Paris COP21 commitments on limiting global warming, the momentum for sustainability in construction is going to continue, giving us ample fodder for comment.

It only remains for me to wish all readers a happy festive season and a sustainably prosperous New Year – see you in 2016!