AIRCRETE AIDS THERMAL DESIGN BUT BEWARE OF A SHORTAGE Marcus Eves, Sustainability Consultant, Darren Evans Assessments


Marcus Eves 3The demand for Aircrete blocks has been steadily growing over the past few years. This can be thanked by a combination of the change in building regulations (Part L 2013) and a housing crisis that has led to strong growth in the residential sector.

With Part L 2013 putting more emphasis on the requirement of an even more thermally efficient fabric, through compliance with the Fabric Energy Efficiency Target (FEE) Aircrete blocks have become the preferred choice to achieve lower U-Values and better PSI Values (Thermal Bridging/heat loss at junctions) and an overall easier route to compliance.

The pace of the industry growth and a lack of raw materials have started to cause a shortage of Aircrete blocks, unwelcome bad news which is slowly rippling through the construction industry.

Pulverised Fuel Ash (PFA) is the main waste product from coal fired power stations and this raw material is integral in the production of most Aircrete blocks in the UK. This lack of material could similarly impact on other concrete blocks, cement and ready mix concrete as these products also use PFA.

A handful of factors have combined to see levels of PFA production drop. A mild winter has reduced the overall level of electricity generation in the UK, lower gas prices has seen electricity generators burn less coal and more gas and as we drive ourselves forward to a greener energy infrastructure reliance on coal power has diminished and will continue to do so.

There is potential to import PFA from coal fired power stations across Europe, but this has never been needed before so the transportation network and infrastructure just isn’t there yet. For now, the most important thing to do is be aware and plan ahead.

A change from Aircrete blocks to a denser block will ultimately see a rise in emissions through high heat losses through the walls and the junctions. This will cause some buildings to fail to meet the Emission and FEE targets, where previously the design assessment was compliant. Compliance with Part L can still be achieved with a change in blockwork as long as the assessor is informed early enough to propose ways to offset the additional CO2 and heat losses.

So the advice is to anticipate the shortage and to begin to design denser blocks into your SAP and SBEM calculations as early as possible.



ZERO CARBON HOMES – BACK AGAIN OR JUST BACK ON THE AGENDA? Graham Suttill, Sustainable Buildings Assessor, Darren Evans Assessments


Yesterday during the Lords Report Stage of the Housing and Planning Bill, the House of Lords defeated the Government on the zero carbon homes amendment. The defeat – by 48 votes – could see the reintroduction of Zero Carbon Homes, the on-site carbon compliance standard, the Government, rather surprisingly, scrapped last July.

So all good news? Well yes and no. Whilst it is a clear sign that there is still much belief in the Zero Carbon Homes standard, the Bill will now go back to the Commons and could enter months of prolonged to-ing and fro-ing where both Houses of Parliament seek to pass their respective versions of the Bill. But the outcome could see Government ensure all new homes in England built from 1 April 2018 achieve the carbon compliance standard.

It’s fair to say, the scrapping of the policy was met with very little – if any – support.  In the eyes of many it was culled post-election so that housebuilders had one less hurdle to jump through and in doing so would help to kick start housebuilding. However this is a very naive and short term view. Killing Zero Carbon Homes simply reinforced the view that the Government has very little understand of green policies and any idea in terms of a long term strategy to create more sustainable housing.

On the back of last week’s support to the COP21 Paris, which saw over 170 countries sign the agreement, the support for Zero Carbon Homes is understandable. But if Zero Carbon Homes is going to rise phoenix like from the ashes, the question is, is it back for good or just back on the agenda?

The hope is that it is back for good. The industry has not lost faith in it and there is still momentum and desire for zero carbon homes. For example, there is still innovation in products and technology that are striving to make zero carbon homes more easily achievable, regardless of whether it is mandatory or not.

It is welcome news but this is a long way to go. However it does demonstrate there is still Parliamentary support for zero carbon homes and its reinstatement will be met with open arms from across the industry.

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.


Government Timber Procurement Policy – What Clients Need To Know Harry Hazel, Darren Evans Assessments

FSC Germany (Forest Stewardship Council Germany)Responsible timber sourcing schemes have been around since the early 1990s and are now commonly used as accreditation for sustainable building projects. Illegal logging has been a long-term problem globally, with recent efforts to tackle it such as the EU Timber Regulation of 2013 not solving the problem. Particularly acute in terms of plywood from China, the issue was highlighted in a report early this year by the UK enforcement agency for the regulation (NMO) which found that only two of 16 plywood importers identified had due diligence systems that met regulatory guidelines. In addition, areas such as Brazil continue to see removal of large areas of rainforest with reports that seven times the size of New York City has gone over the past year despite government efforts to tackle the problem.

The best known responsible timber sourcing scheme was set up by the Forest Stewardship Council (FSC) in 1993 as a global certification scheme that guarantees timber and timber products have come from well managed projects. The Building Research Establishment (BRE) put responsible sourcing of timber at the top of its agenda in the development of BREEAM, making it a mandatory element within any BREEAM assessment and recognises FSC certification as an indicator of responsibly sourced materials. In the light of this,  the issue should be high on the agenda for any project team involved in a BREEAM assessed project.

The UK Government’s Timber Procurement Policy closely aligns with the EU and requires any timber to be legally sourced or from sources which are licensed by the EU’s FLEGT (Forest Law Enforcement Governance and Trade) body or come from ‘equivalent sources.’ The FLEGT Action Plan was established in 2003 with the stated aim to “reduce illegal logging by strengthening sustainable and legal forest management, improving governance and promoting trade in legally produced timber.”

In terms of what clients need to know, the crucial point is that any timber used on site – from that used for construction to timber used for hoardings – needs to be legally sourced. The most easily identified way of doing this is the FSC label, as this indicates there is a traceable trail of where the wood has come from. The chain of custody certificates that come with FSC certification can then be used by BREEAM assessors to show that the suppliers of the wood use legal and sustainable timber, as they represent the whole life cycle from tree felling to production to distribution to supplier.  As an alternative to plywood, which is where many responsible sourcing issues arise, is OSB which can be locally grown and produced and can thus offer a much better environmental score than timber as well as better performance characteristics.

In addition, to show compliance with responsible sourcing in an individual BREEAM assessment, project teams need to produce delivery notes from suppliers on the project concerned in order to create an auditable trail. These not only show which suppliers have been used, but whether they are using FSC accredited timber and have chain of custody certificates.

So in short, clients looking to establish responsible sourcing for timber firstly need to ensure that they can obtain FSC and Chain of Custody certificates from suppliers to show they are in compliance with Government policy. They also need to ensure they collect the delivery notes from the project to show that all timber used is legally and sustainably sourced. Lastly, they need to pay attention to where timber is used across the whole of their sites, as irresponsibly sourced timber anywhere on site will mean a breach of regulations.

BREEAM Is Looking Good At 25, But Needs To Share The Love – Darren Evans, Managing Director, Darren Evans Assessments

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This week BREEAM turns 25, and it has been a great quarter century of setting the standard for sustainability globally, with well over half a million buildings now certified in 70 countries and a robust and comprehensive assessment system. The question is whether enough people know it is much more than just a tick-box standard, and is in fact a realistic way of galvanising a whole project team and building users towards sustainability goals.

BRE has just launched a new all-singing and all-dancing website to coincide with its birthday, and it features a nifty ticker counting the buildings currently covered. At the time of writing, it’s an impressive 531,644 certificates issued which is a lot of buildings worldwide, which are demonstrably better on sustainability across nine criteria, whether the emphasis is on health and wellbeing of occupants, responsibly sourced materials or robust project management of sustainability. Perhaps the most important and effective part about BREEAM is the way it can drive the focus on reaching the targets throughout a project team and in the client to help everyone push towards the same goal; this also fosters substantial pride among users in their buildings post-completion.

With 2.2 million buildings in total registered to be assessed, there is a lot to come, making this truly a global movement and one in which we are key UK players as sustainable building assessors regularly using BREEAM. BRE has made a very strong case that high quality buildings don’t have to be prohibitively more expensive, showing that it is possible to get a Good rating with no extra cost, whatever the site, and Excellent adds only an extra 2.5% to the capital cost. Making BREEAM realistic in this way has helped to broaden sustainable building across many areas of the UK. Even the higher level Outstanding schemes which add more to the capital cost only have a payback of a few years in lower energy and water bills, so investing in BREEAM makes financial sense, especially when you look at the higher value placed on such buildings for example by commercial tenants.

BREEAM is also about to fully launch The Home Quality Mark as national standard for new homes, pared down slightly from the previous version after its industry consultation. This could, if embraced by both homeowners and as a result the housebuilding sector, be a worthy and more all-encompassing successor to the Code for Sustainable Homes.

However, it’s not all good news, despite the many schemes which have become part of the BREEAM family, there are many non-believers out there, who believe that BREEAM is too bureaucratic, too inflexible, or focuses on a tick-box approach to achieving credits which might not take a truly holistic view of a building or the design solutions being proposed. These beliefs are probably the result of a lack of awareness of what BREEAM is or how it currently works, and an indication that there is a lot more to do to engage with the wider construction community to clearly explain what it is all about.

Complaints have been aired that BREEAM can focus too much on prescribed elements within a building to obtain credits, and it’s arguable that BRE could be more transparent on the calculation methods it uses in order to help reassure people and bust some of the myths. It could also disseminate more widely how the ‘innovation credits’ which BRE introduced can enable project teams to produce solutions which may not be in the prescribed list, but which can still gain credits because of their fitness for purpose, meaning they don’t in fact have to ‘tick all of the boxes.’

BRE needs also to do more to simply advertise the benefits of BREEAM to the construction industry, to ensure that it is not simply seen as a technical standard for the sustainability community, but is for everyone and has particular benefits for building occupiers whether they are major corporates or homeowners. BRE knows that property owners are able to rent their commercial space out faster if they have a BREEAM certificate, and this story needs to be told to back up the case for investing in the certification. It also needs to communicate the fact that it has a developed a crucial Refurbishment and Fit-Out version of BREEAM, which will reward good sustainability for performance for the many existing buildings we need to address.

Despite the fantastic achievements of BREEAM there are a great many people out there in the industry who do not yet understand it or the benefits it can bring. For example, under the GLA’s London Plan all boroughs are required to BREEAM assess all new developments, and many individuals tasked with doing so will be on a steep learning curve to a full understanding of the benefits as well as the broad scope of the assessment.

I wish BREEAM a very happy 25th birthday and remain a strong supporter. Maybe as part of the ongoing celebrations BRE could focus on disseminating the value proposition which BREEAM offers as widely as possible in the UK to bring everyone into the party.

District Heating: It’s Becoming Centrally Important – Marcus Eves, Darren Evans Assessments

Marcus Eves 3

There is an old saying that there is nothing new under the sun and district heating certainly isn’t a new idea. The concept, also known as community heating, has been around for decades and has been implemented successfully throughout the world, particularly in urban environments and other areas of high building density.

District heating is a straightforward idea which can bring fantastic efficiencies and while its uptake in the UK has been relatively slow, the agenda to combat fuel poverty may mean this is about to change. Simply put, heat and hot water are supplied to a number of buildings from a central energy source via a network of insulated pipes. Heat exchangers in each of the buildings deliver the heat to them, removing the need for individual boilers or other heat source, with the network acting as a normal wet system.

The drivers for district heating in the UK are also well established. Regional and national targets for energy saving and carbon reductions are forcing councils to implement as many sustainable strategies as they can think of. You will not read a Core Strategy or Local Development Plan without coming across the phrases ‘sustainable communities’ or ‘district heating.’

Many UK local authorities are taking a keen interest in district heating following the success that has been seen in some nearby European cities. Copenhagen for one has had a network since the 1970s, and today this delivers 98% of the city’s heating needs. London and the rest of the UK have come a little late to the party however and will view this figure as an impossible goal. There are currently not enough heat networks so retrofitting to meet demand is a certain challenge on the infrastructure.

Local and Regional policies are however pushing for the need to future proof. The beauty of heat networks is that once an insulated network of pipes is laid, what is connected at the end to produce the heat can change and adapt as the environment around it changes or a technological development is achieved. This could involve replacing fossil fuel plant with renewables such as biomass or tapping into waste energy, such as the scheme currently being considered to utilise the 25°C air which is vented all year round from the London Underground.

If you are building a major development within the confinements of the London Plan (the GLA’s overall strategic plan) it is mandatory to consider decentralised generation of heat and power. The expectation is, where appropriate, that the developer’s proposals should seek the follow a hierarchy as follows: 1. connecting to an existing heating or cooling network, 2: implementing a site-wide CHP network, 3. installing a communal heating and cooling network. Any system should be future-proofed and designed to connect to a district network if one becomes available.

When designing the layout of the site, thought should be given to its density and optimising installation of a system. This will include understanding the energy demand of the site, identifying locations suitable for heating plant and associated hot water storage as well as internal layouts for the risers required to move the water around the building.

There are a number or online tools which can help developers maximise the potential savings available for implementing community and district heating. Arup for example has developed a Carbon Calculation Tool which allows developers to estimate CO2 savings for new and existing district heating schemes with different sources of heating. Another useful resource is the London Heat Map which has been developed as an interactive map which identifies where existing heat networks are located and areas outlined as having potential for decentralised energy.

Where a site has been identified as suitable for a community heating system, consideration must be given to the use of Combined Heat and Power. This is a well-known approach to simultaneously producing electricity and heat onsite increasing energy security. Further to simple environmental benefits, the introduction of CHP can bring both social and economic benefits in the form of low cost electricity and affordable warmth, lower life cycle costs and lower management/maintenance costs. The system must be sized adequately in order to ensure a constant operation which will maximize the potential savings.

With stricter regulations on installation, regulation, maintenance and control the installation of a district or community scheme enables the efficient transportation and use of heat for a wide variety of users. There are unrivalled opportunities to allow a broad range of energy generation technologies to work together to meet demand for heat enabling fuel flexibility. Although capital cost can be high, the whole life cost benefit from infrastructure which can be expected to last much longer provides a means of securing significant reduction in CO2 emissions through the optimisation of heat supply.

The opportunity for improved local fuel security via district heating must be seen as key to helping to provide a long term method of tackling fuel poverty.

Reasons To Buy Into Breeam – Michael Brogden, Director, Darren Evans Assessments

BREEAM in-use Certificates world map September2012

BREEAM was developed 25 years ago by the Building Research Establishment as a comprehensive assessment tool for demonstrating a building’s sustainability against a wide range of criteria. During its lifetime it has grown to become an internationally respected system of established benchmarks and industry recognised measures for evaluating the specification, design, construction and use of buildings. However, what are the key reasons that you might consider implementing BREEAM on their project?

If you are an architect or a specifier, one of the best reasons to choose BREEAM is that the broad range of environmental criteria which it covers enables you to demonstrate your firm’s variety of skills in delivering environmentally friendly as well as energy efficient buildings. The process of achieving the credits required within each of the relevant categories within BREEAM encourages designers and contractors to seek innovative ways of delivering projects and to consider environmental aspects at a much earlier point in a project than might normally be the case.

The certification demonstrates that reducing environmental impact is high on the agenda of the whole product team, and that the design team has managed to deliver on that agenda. Buildings certified under BREEAM will have lower running costs, lower water and energy consumption and less waste, and often incorporate passive design principles, renewable energy and responsibly sourced building products with lower embodied energy. Therefore, it is a sign that a more thoughtful approach has been taken throughout the project.

For building owners BREEAM is the recognised badge that shows they have maximised the sustainability potential of their building. In addition, the rigorous way that BREEAM rated projects are audited and run provides a credibility which gives confidence in the ratings which are produced at the end of the process, whether the building is Very Good, Excellent or Outstanding. This plus the wide and growing awareness of BREEAM across all sectors of the industry enables buildings to be differentiated in the marketplace and command a higher degree of desirability. This is crucial in the commercial sector for example where BREEAM rated buildings are typically rented faster to tenants.

For contractors, BREEAM enables firms to demonstrate best practice when it comes to delivering sustainable construction which for example diverts as much waste from landfill as possible and reuses materials. In addition, certification shows that they are able to reduce ecological damage caused by construction, and are focused on increasing ecological value on sites where possible. Successful BREEAM projects mitigate pollution incidents, minimise impact on neighbours and increase biodiversity, as well as use of local suppliers. Achieving all of these benefits is assisted by the fact that the process of undergoing BREEAM helps improve monitoring of these factors.

Some other compelling reasons to adopt BREEAM:

  • The assessment tool tends to encourage buildings to be designed for longevity and future adaptation, making them more resilient
  • Certification shows that the build reduces ecological damage from construction and adds value to the local community
  • BREEAM helps to create buildings that are fit for purpose for the client via the consultation approach which is inherent to achieving the certification
  • BREEAM buildings provide a healthier environment for users with increased holistic benefits such as natural light and ventilation
  • BREEAM demonstrates that reducing environmental impact is top of the agenda for building owners, architects, contractors, developers and end users.

As it celebrates its 25th birthday, BREEAM is without doubt a success story for the construction industry, helping raise the bar for sustainability in the UK and internationally with a robust assessment system which adds tangible value. With over 425,000 buildings having been assessed so far, that means a lot of projects which are offering healthier, better environments for employees plus a good image for construction’s ability to achieve measurable sustainability improvements.