Tag: AECB

HPH283 : Modelling the embodied carbon of your build – with Tim Martel

Tim Martel explains how to model the embodied carbon of your build using PHribbon, a tool that plugs in to PHPP (Passive House Planning Package).

Interview with Tim Martel

Tim is a qualified architectural technologist and Passivhaus designer. He also works for the AECB and is a course tutor for the CarbonLite retrofit course. Helped by a background in programming he has used his research and experience of working on new builds and retrofits to create PHribbon – a tool which enables people to model the embodied carbon on their build.

PHribbon is designed to specifically work with the PHPP software

While there are other specialists who do work on embodied carbon, PHribbon is unique in that it has been designed to work specifically with the Passivhaus Planning Package (PHPP). This is a benefit because around 80% of the information needed is already in PHPP. The additional information needed will be the things that aren’t covered by PHPP, such as internal walls, floors and roof coverings.

PHribbon front screen

The calculation is built around a RICS document

The Royal Institute of Chartered Surveyors (RICS) wrote a document in 2017 called ‘Whole Life Carbon Assessment for the Built Environment.’ It’s a statement of what members have to adhere to and sets out in detail what is expected of the calculation. While the RICS calculation can only be done once a building is complete, Tim is able to use quantities that are in PHPP to give a good estimate of what the embodied CO₂ of the building is likely to be.

Information is gathered from Environmental Product Declarations

The RICS calculation uses information from Environmental Product Declarations (EPDs), which are documents that work to European EN standards and which quantifiably demonstrate the environmental performance of a product. RICS also go through the whole lifetime calculation with detail on what should be done at each stage and what assumptions should be used. Assumptions being necessary sometimes for standardisation, because of the inconsistencies of different people coming up with different answers even for the same building. With lots of companies producing these declarations, (Tim now has around 200 in PHPP covering many different materials) the challenge might be in convincing manufacturers of products with lower environmental credentials to share their information.

CO₂ results can be shown in different ways

As long as you are able to provide the net internal area (NIA), results can be shown as kilograms of CO₂ per metre squared of net internal area. In addition the graph can be customised to show total CO₂ for the whole building, kilograms of CO₂ per metre squared of TFA (that’s usable space in Passivhaus language), and even CO₂ per occupant.

Awareness is drawn to potential inaccuracies

Tim stresses this isn’t an official calculation, but it does closely follow the RICS standard. There will however be some inaccuracies, and these are highlighted by a colour coded system in PHribbon to draw attention. Some EPDs they can be fairly certain about so will be coloured green, but others that they’re less confident of will be orange or red. They might be ones that are based on RICS assumptions like 300km being the assumed transport distance from various manufacturers to the site if its a national product, whereas in reality it’s likely to be more or less than that.

Generally speaking, the information is likely to get more accurate as more EPDs are produced, and with more available it’s highlighting just where the missing information is. In particular, it would be useful to show information for the end of life stage, and include reuse and recycling benefits.

Results can be tailored to show alternatives

With several examples already completed, Tim says his findings show a typical semi-detached house as having around 14 tonnes of CO₂ for the whole life of the building, with about 10 tonnes of that just for the materials themselves. The benefit of using PHribbon is that comparisons can be made in a graph by using different options, such as what the figure might be if the house was made out of brick, as opposed to timber.

Example of whole building using timber, PIR versus brick

Example showing 100m2 wall using timber, cellulose versus brick

More information is needed about the end of life stage

With some of the more typical timber constructions where I-beams and cellulose are used, both of those have quite a large storage component so a large bar represents that storage which offsets all of the emissions in the RICS calculation.

Tim says there’s a catch with this though, as one of the assumptions is that in order to include storage you have to do a full life calculation. That then uses the RICS assumption that 75% of the timber is incinerated at the end of life stage, with the other 25% going to landfill. Unfortunately there isn’t currently enough information about recycling and reuse to produce those in the EPDs as an alternative.

“If you could say, ‘this building has been built so that it can be taken apart and recycled. This material is ideal for being recycled so it can be made into OSB, MDF or anything’, if that can be done and we can prove the figures for it with an EPD for that process then you could legitimately add that as another option.”

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March 25, 2020
HPH282 : How to share knowledge, test and debunk! – with Nick Grant

Nick Grant shares his thoughts on the lessons learned from 30 years of the AECB (Association of Environment Conscious Building).

Interview with Nick Grant

Nick Grant from Elemental Solutions is a Passivhaus consultant and also Technical Director of the Passivhaus Trust. He’s been on the podcast a couple of times before talking about value engineering and integrated design.

Nick has had a long involvement with the AECB (Association of Environment Conscious Building) and at the conference last year, celebrating 30 years of the AECB, Nick and Alan Clarke gave a presentation about lessons that have been learned during that time, and Ben was keen to explore this further.

The AECB has an openness of critical thought

Nick highlights that the AECB has a strong ethos of accepting when you’re wrong, realising mistakes that are made and learning from each other’s mistakes. That’s not to say it’s an easy thing to do, particularly when you’ve spent years becoming an expert in something and then admitting that’s perhaps not the best way of doing it.

“So, some of these things, it’s better to know than not know because you could carry on for the rest of your life to your grave doing things that turn out to not be worthwhile.”

Becoming aware of all the negatives and then getting rid of them, leaves you with the bits you want, which turns it into a positive.

Passivhaus works!

Nick explains that when he built his own house, he’d heard of Passivhaus bu there wasn’t enough information in English to know much more, other than it was about thermal bridges and airtightness. His own house was designed intuitively without any energy modelling, because with the walls over a foot thick and a foot thickness of loft insulation, there didn’t seem much point. It was only later when they modelled it that they realised it wasn’t great, primarily because of the form factor.

Nick’s self build project

Sheila makes the engineered DIY rafters (to save a bit of cash)

Nick and Sheila’s house

House interior

The term ‘thermal bridges’ wasn’t in the Building Regs, and while they knew what it meant, they didn’t realise that around a third of the heat could be escaping through them if they weren’t dealt with. It’s only now, having done the analysis on hundreds of buildings, that they have a learnt intuition.

Nick attended the first Passivhaus conference, back in 2007, partly to debunk it, and partly out of curiosity. But having been to the talks and seeing some of the buildings, he realised that it actually worked and was very impressed with what he saw.

Whereas before there would be arguments about thermal mass and all sorts of discussions that were points of opinion, now Passivhaus is a simple model that can be used to give the answers.

It’s important to use critical thinking and questioning

This is something that Nick says the AECB has been particularly good at, and should be a fundamental part of learning.

Not everyone does this however. Particularly among some designers there can be a resistance to it, because of not wanting to have constraints that will mean their visual design won’t work.

He would rather embodied carbon be kept separate from the Passivhaus Standard

In the early days of the AECB, Nick says where there tended to be more emphasis on using natural materials, then the performance aspect had to be abandoned and the building justified in other ways, such as lower embodied energy.

Nick says this doesn’t have to be the case and just because you might be talking about one aspect, it doesn’t mean the others have to be ignored.

“I think the problem is when you pursue one and it causes a problem for the others or it excludes the others. So, if the energy performance requires things that are ugly or polluting or something like that, then that’s a problem. But that’s not what I’d want to do. So, it’s a compromise.”

In terms of whether Passivhaus should go down the route of incorporating more about embodied carbon, Nick doesn’t believe that it necessarily should. He would rather it be kept separate from the standard, otherwise there can potentially end up being trade-offs that happen in other green building standards, like where there’s lower embodied energy there can sometimes be higher operational use.

The problem with embodied energy is complex

There are conflicting views, with a good example being timber.

“Depending on how you do the accounting, some people see timber as a negative thing and that leads to the idea that the more you put in the building, because you’re locking up carbon, even to the point where the building is not emitting carbon until ten years into the future when the operational has overtaken the embodied.
We think that’s nonsense. Most of our buildings do use timber but we don’t see that as negative. It’s still every time you cut down a tree and turn it into a building, carbon is emitted. I’m not an expert but I’m assuming there’s less emitted than if we use steel or masonry and so on. That’s why we like to use timber. But we don’t see it as negative.”

A timber frame construction using i-beams

Off-setting alone isn’t enough

When it comes to off-setting, Nick says there aren’t enough trees that can be planted to do all the things that we need for building, flying, running vehicles, heating homes, making electricity etc.

“We’ve got to do off-setting in the sense that we’ve got to plant loads of trees and we’ve got to do all that stuff. But we can’t do that instead. We can’t say, ‘I’ll fly to America and plant a tree and that’s fine.’ We’ve got to do the not flying to America and the planting of trees and the not using energy. There’s not enough off-setting possible.”

Existing building stock is a problem

Nick says that most of his work is new buildings, partly because it frustrates him that the new buildings of today are being done so badly and are the retrofits of the future. But a bigger challenge is what should be done with all the existing building stock, and this is something that he doesn’t have the answer to.

One thought is to retrofit them all to Passivhaus standard, but that seems incredibly difficult, particularly with listed buildings. In some cases where they’re in a state of disrepair, adding in extra insulation or triple glazed windows is a no-brainer, but a lot of retrofit isn’t like that. Many are perfectly good buildings that are going to cost nearly as much to retrofit as a new building would cost.

Designing buildings for the future gives a false sense of security

Nick says that designing buildings that can adapt to higher temperatures or flooding in the future can be a dangerous thing as it gives a false sense of security that we can survive this. We need to be designing for the hot summers and extreme weather that we get now.

With so much change happening so quickly, such as a rise in fascism and better awareness of climate issues, Nick says it’s hard to predict even one year ahead.

“But that’s what keeps us going I suppose, thinking that at least we’re doing the right thing. On one level, incredibly pessimistic; absolutely can’t see any way this is going to end well. But at the same time, what else do you do?”

Photo credit Bill Butcher

The AECB has had a big impact

Nick explains that although the AECB is a small organisation, it has had a big impact, with most of the best performing buildings having had AECB members involved.

In contrast, he says things like the World Green Building Council seemed to be made up just of people who had paid to have membership, with no Passivhaus buildings, and none that the AECB would consider to be exemplary.

“Within our little group, it feels like things are moving forward. But if you step out of the bubble then it feels like it’s unknown what we’re doing.”

Image credit Lancaster Co Housing and Eco-Arc

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March 18, 2020
HPH246 : Self build mortgages that promote sustainable living – with Paul Ellis from Ecology Building Society

Paul Ellis, Chief Executive of Ecology Building Society, explains their approach to mortgages that reward energy efficiency and sustainability.

Interview with Paul Ellis

Paul Ellis was an early investing member back in 1981 when Ecology Building Society was formed, and has been Chief Executive since 1995.

Founding members had a shared interest in environmental causes

The ten founders had met through their involvement with the Ecology Party; the forerunner of the Green Party, and had a shared interest in self-sufficiency and low-impact living.

They were individuals looking to buy properties to renovate to reasonable energy efficiency standards, and without doing too much work. What they found was lenders were very restrictive and uninterested in providing support. They would demand certain works such as ripping out stone floors and putting in damp-proof courses that weren’t really needed, but that they felt would minimise their risk.

“So, they’d often say they’d lend the money, but only once all the work is done, which wasn’t the point because everybody wanted to do their own work, be self-sufficient and learn building skills. So, they would be forced immediately into trying to get others to do the work and they were probably not going to have those kinds of funds available.
So, the building society was setup to really encourage that ability to take properties and bring them back into good use to a reasonable standard, but not to provide expensive kitchens.”

They are the youngest building society

At the time they decided to set up a building society, there hadn’t been another done for quite a while beforehand, and they are still the youngest in the country. Paul believes a change in the regulations is the reason for this. In 1981 they only needed ten investors with a maximum of £5,000 to actually start the building society. The authorities caught wind of it and changed the rules to increase that amount. Luckily they managed to get the paperwork signed with five minutes to spare before the rules came into enforcement!

Building their own premises seemed a natural step

With the business growing it was necessary to find new premises, and after considering renovation they decided that building their own offices would be the best way forward. It could incorporate some of the techniques they were asking their borrowers to consider, and be a bit of a test to see what the issues were. And while the building has largely been successful, there are certain things they would now do differently.

The building dates back to 2003, before Passivhaus was well-known in the UK. If they were to do it again, or when they extend it, they would use Passivhaus concepts.

Paul says they were fortunate at the time to have the advice of eminent energy efficiency experts, although they had to compromise some of the ideas slightly to create a warm, welcoming space to live and work in.

There are two distinct elements to the building. One part focuses on long-term energy use, with large amounts of concrete but highly insulated and built to a good level of airtightness.

The meeting room area of the building was entirely constructed from straw bales, with a clay plaster render on the inside. Some of their members even came along to help with the construction while learning the techniques of building with straw.

Throughout the building they have tried to make as much use as they can of recycled, reclaimed and other materials that have low embodied energy.

Get early advice

Paul would encourage anyone at the beginning of their self build journey to take a look at their website or give them a call to discuss their plans. While they wouldn’t immediately be able to give approval, they might comment on their ideas of budget and whether they think it could be viable for what is being proposed.

In some cases they can be communicating with people for years who haven’t yet found their plot, but the majority of time people will already have a deposit and a plot.

“For us to make a decision, we have to be sure that there is something here which is going to work in terms of energy efficiency or wider environmental considerations, and so it’s hard for us at the outset to give more than a rough picture of what we can contemplate because we don’t know the nature of the building.
For us as a lender, the actual nature of the building, the finished product, is quite important to us. For other lenders, it would be more of a focus on the finances. For us, it’s what the building will achieve.”

During initial discussions they would ask about the techniques and materials the borrower plans to use, and take a view on whether or not they think it’s a project that will work, by getting an understanding of whether the individuals understand those techniques and whether it will work in practice against their budget.

Paul says that a good development has been more borrowers these days employing architects who have a strong knowledge of these techniques.

Payment stages are flexible

Typically, their projects will have staged payments, although they aren’t set at a predetermined, fixed stage. Instead the borrower contacts them to say they’ve done a certain amount of work, at which time they will get it valued and release money against that.

“That introduces a certain level of flexibility. Obviously, internally, we do track and monitor the progress of the building to make sure that it’s remaining on track. And that’s because we’re looking after our members’ money. We’re making sure they’re secure. But within that, we can be quite flexible when those releases will happen to suit the circumstances of the borrower. And that might be that they’re tying into other financial resources as well. They might have monies that are not quite available or whatever, so we’ll take that into account.”

Understand your plot

Paul advises buyers to know their site well, to avoid unexpected costs and delays. Understanding issues with boundaries, hidden structures and general groundworks will be an advantage.

He also recommends a budget contingency of ten percent, which is something they will look for in the costings.

Renovation projects are encouraged

Ecology have a varied client base, but not too many first-time buyers. Those they do get tend to have been gifted a plot or had help with their funding, and more commonly are carrying out renovations.

While Ecology like to support renovation projects, which was mostly their emphasis in the early days, the tendency now has been for more self builds.

“And you can see why, in some respects, because there’s been a lot of development in green building techniques, in products, and you can start with a blank sheet and design in energy efficiency from the start.”

From an environmental point of view, Paul sees the need to improve the existing housing stock. They are working with companies, cooperatives and government departments to find a way they can create models to encourage more people into taking on renovations and retrofits, by providing systems of support and information, and making it easier for people to engage.

Their self build clients tend to already be fairly well informed and have carried out research and engaged with organisations like the Passivhaus Trust or AECB. And for those less well versed they might question certain aspects, for example, whether they need all the renewables when they haven’t really considered insulation.

Another form of construction they are keen to encourage are kit homes that are semi-constructed off-site. They often come with some guarantee of energy efficiency and avoid many of the pitfalls that can occur on site.

Financial benefits for the most energy efficient

Ecology provide discounts for the full term of the mortgage, based on the property’s standard of energy efficiency upon completion, with Passivhaus giving the maximum discount.

Progress is being made

Paul believes in their early days they were lone pioneers, but gradually now they are seeing advances in the green building components industry, with exciting new products and more companies trying to do the right thing.

“So, it’s almost like despite the drift of government policy, business, companies, individuals, cooperatives are leading the way on this because they know it’s not only good for the planet, it’s good for society, it’s creating sustainable jobs, and it is beginning to happen.”

He is also seeing a push on the Green Finance Initiative, looking at ways to increase the flow of funds to green investment products.

Something that Ecology are doing to assist with this is they’re working on a project to create an energy efficiency mortgage model that would be available across Europe. It would enable more mainstream organisations to create preferential financing for mortgages on properties that are making a difference to our carbon footprint.

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April 17, 2019
HPH194 : What are the hidden costs of building a house? – with Paul Testa
Paul Testa from Paul Testa Architecture talks about how to predict the costs of a house build and shares his tips on limiting a self-build budget.

Interview with Paul Testa

Architect Paul Testa’s interest in construction led to coordinating and teaching the technology course for the MArch in Architecture at Sheffield University. He’s also a tutor and lecturer for the Sustainable Architectural Studies Masters course at Sheffield University. He is a member of AECB (Association for Environment Conscious Building).

Build cost is not necessarily ‘cost per square metre’

Paul aims to help clients gain realistic expectations of their project’s costs. They start by assuming a mid-range, bespoke new-build would cost roughly £1500 a square metre. They then use their cost calculator to add in additional costs, taking into account factors like slope of the site, higher specification and external works.

To price the whole project, Paul says self-builders should include connecting utilities, landscaping, and contingency in the overall build cost. If an architect or builder prices your project at £1500 a square metre, remember this may not include all the costs of the build.

A steeply sloping site

Fees are affected by more than just project size

It is important to have accurate cost predictions for your build and these do not just relate to square metres. Paul explains that the cost of consultants isn’t tied to the size so much as the complexity of the project.

Some costs, such as surveys, might depend on both the size and the complexity of the project. Paul recommends adding 30% to your construction cost for planning and building regulations fees and any other costs. Some of these don’t change with the size of the build, so the fee will be a greater percentage of the build cost for a smaller project.

Utility costs can vary from site to site

Paul has found the cost of connecting gas to be quite consistent, but not so for the electricity supply. The cost can vary hugely depending on the work involved in making your connection, and remains unknown until the application is made. Furthermore, Paul warns that there is no room for negotiation, saying, “It’s a captive market unfortunately.”

“Most contractors won’t have sufficient insurance for the whole project”

Contractors will have insurance to cover their liabilities (public liability and employer’s liability insurance) and potentially for their equipment on site. The architect also needs professional indemnity insurance and public liability insurance to cover the implications of design decisions. Paul advises clients to procure insurance to cover the new building and materials.

Claiming back VAT may depend on your contractor

Some contractors don’t pass on the cost of VAT: the client never sees that cost and the contractor just claims it as part of their quarterly VAT payments. This may be beneficial for clients who don’t have the cash flow to pay upfront for the build plus VAT and then reclaim the VAT later.

Often clients prefer to procure large single ticket items (e.g. windows) themselves, to avoid the contractor’s overheads and profit. In that case, Paul reminds clients they should budget to cover that VAT cost until the end of the project.

Keep back at least 5% of your budget as contingency

To deal with unknowns such as the ground and weather, Paul recommends having “something there to cover you, a minimum of 5% but more generously 10%”.

He warns that stretching both construction budget and contingency “can be quite dangerous.” He advises spending more at the end if you have money left, rather than pushing to do absolutely everything without compromise.

Expert advice during planning helps predict cost more accurately

Although he cannot completely mitigate the risks of unknown costs, Paul ensures that the correct investigations are done as early as possible to try and minimise additional costs. “Certainly on the bigger jobs where there is more scope for value engineering,” he says, “we will try and bring a quantity surveyor or an estimator in at roughly the planning stage.”

This expert can give a budget cost for the build. If it doesn’t fit within a client’s budget, Paul’s team can make changes before the planning application is submitted, avoiding later amendments and resubmissions.

Avoiding the tender process can actually save money

Ideally, Paul likes to find a contractor he wants to work with and that the client is happy with, who will “buy into” achieving the building at the budgeted price. He relies on the expertise of the chosen contractor to ensure that the detailed design matches that budget.

Although Paul acknowledges the benefits and drawbacks of both routes, he doesn’t believe the tender process is the best way of procuring a building, saying “We actually incentivise that in our fees and we charge less for a negotiated price with a contractor than we would do for dealing with a full tender process.”

Contractor availability can be as important as cost

Paul works with a pool of preferred builders, although this can change over time. He explains that the best contractors can be booked up to two years in advance. Although clients might be disappointed by delays, they usually come round. “If they want the very best product, they want the very best people to do that,” he says.

Engaging the contractor earlier in the process can mean that delays are avoided. Having agreed an approximate start date with a contractor, Paul stays in touch while developing drawings, maintaining agreement on budget and timescales. He says, “By the time we’re ready and the contractor’s ready, everything’s drawing together.” However, he adds, “it doesn’t always work that perfectly.”

Tender processes have their own drawbacks. A four to six week process can lead on to reviewing prices, interviews, and value engineering. After all this, the contractor’s availability might be delayed another year. It can be difficult for a client to ignore a much cheaper quote but Paul warns, “Normally, if it’s too good to be true, it probably is.” The project ends up costing as much but with extra difficulties.

A passive house can be built for less than £50,000!

In 2013 Paul’s team submitted a design to the National Self-Build and Custom Build Association’s annual competition ‘Self-build on a Shoestring’. The brief asked for a detached family home, on a very simple flat plot, for £50,000 or less, including all materials and specialist labour but assuming utility connections were already in place.

Paul’s approach was to make “a simple construction that can be built by the average self-builder”. While mainly a “materials only” cost, it included specialist input such as commissioning the MVHR system, certifying the electrics, gas installation and digger and scaffolding hire.

Not only did their design offer a 70m² family home for around £45,000, it was also designed using the passive house planning package. Paul says, “We delivered a building that achieved passive house for less than £50,000 and would be a compact but very comfortable single family home.”

Delivering build elements constructed off-site to manage costs and time on a steep site

Five top tips to keep build costs to £50,000
- Remove main contractor: get hands on, do physical work, and do your own project management
- Reduce risk by choosing a manageable construction method, such as a simple softwood timber frame.
- Minimise the number of materials.
- Maximise the function of each element, e.g. exploit oriented strand board (OSB) in three ways: as an airtight layer, internal wall linings and structurally, to stop the building twisting.
- Choose larger format materials with cheaper production and installation costs, such as fibre cement slates rather than timber cladding.
Find out more

Visit the website of Paul Testa

Follow Paul Testa on Twitter

Follow Paul Testa on Facebook

Visit the website of AECB (Association for Environment Conscious Building)

Transcript

Download a transcript of the interview with Paul Testa

Please connect with me
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October 13, 2017
HPH116 : How do you find a good builder of low energy homes? – with Mike Whitfield from Mike Whitfield Construction

Mike Whitfield, from Mike Whitfield Construction Ltd, explains what to look for if you’re trying to find a good builder for a successful low energy building project.

Interview with Mike Whitfield

Based in Herefordshire, Mike Whitfield’s name comes up time and again when the words ‘Passivhaus’ and ‘builder’ are mentioned in the same sentence, and if reputation alone is anything to go by, then Mike is certainly a leader in his field.

In the late 1980s he worked with a builder using reclaimed and natural materials, even before they had any real notion of energy efficiency. His interest in this way of building was piqued in 1996 when working on a job with an energy consultant, and this has led to a gradual move towards constructing energy efficient buildings, to the point where his company specialises in building to Passivhaus standard. During this time, they have been continually working to improve their assembly methods and detailing.

Perhaps not being your typical builder, Mike has been to the AECB conference a number of times (at which he has also attended as a guest speaker), and has found that it has been a very sharing environment where people are learning a lot from one another.

Look for someone who has a genuine interest

Mike believes that if a builder has a reasonable level of competency, is prepared to learn, and looks at a previous job and thinks how they could have done it better, then they have the ability to progress quickly.

He recommends using the AECB as a starting point for finding a builder. Even if they don’t have experience of Passivhaus, it is likely that they at least have a real interest in low energy buildings.

The beauty of Passivhaus is that it is measurable, so anyone claiming to be a specialist in the field can be judged by their results. Mike explains that this is the reason why he has been so busy the last few years, because once you have a track record of being able to build an airtight, thermal bridge-free home, then people will come to you because they know you can actually deliver it.

Attention to detail is the biggest difference from traditional building

On a traditional build, with a good plasterer and second fix carpenter the results can look okay! It doesn’t work that way on a Passivhaus building.

Mike explains that it’s not just about completing the tasks, but ensuring they’re done in the correct order to get it right and save considerable time and money.

“The biggest challenge in building, is doing things in the right order really. And it sounds a lot easier than it is. To get the materials there, and the right people there, at the right time so that everything flows in the right order, takes quite a bit of experience.”

The steps to building a high quality, energy-efficient home

A typical project for Mike would ideally begin by working with an architect that is “on message”. If the architect is inexperienced then they would usually recommend bringing a Passivhaus consultant on board to assist.

A good set of drawings should be completed by the architect for the builders to work from, with the opportunity for Mike to have input if he can see where improvements can be made.

The windows need to be ordered in advance so that they are there on site within a couple of weeks of starting the job. They prefer to put the windows in as they’re building, as it’s easier to do and also helps to protect the site.

Other stages include insulation and airtightness, first airtightness test, first fix electrics and plumbing, plastering, completing the MVHR system, second fix tiling etc.

Garway – photo by George Mikurcik

Building to Passivhaus standard takes time to learn

Mike’s company has 8 full employees, but even for skilled carpenters or builders who aren’t used to Passivhaus it can take at least a year or two for them to fully get their heads round.

“They’ve just simply got to do that length of time to experience enough jobs to fully understand all the pitfalls really and to see where the problems might arise.”

Work to the builder’s programme

Mike thinks that when selecting your builder it’s important that if you’ve found someone who you think is the right person then you should work to their programme and be philosophical about waiting for them to start. He explains that the most stressful part for him is turning up to start the job on time! It can be very difficult to predict, given the whole process can sometimes start up to 18 months earlier. Even at the point of signing contracts and ordering windows it can still be 6 months before they start on site, and dealing with extras can easily see that 6 months become 7 or 8.

Ledbury – photo by George Mikurcik

Passivhaus requires a higher level of supervision

Mike tries to have one main job at a time, though there are generally two on the go: one being finished and the other being started. Having any more jobs would mean he wouldn’t be able to get round the sites easily to provide the level of required supervision. Even experienced people that have been working with him for 10-15 years still need a certain amount of help and supervision, because not every project is a straightforward box shape.

Maintaining good relationships is key to the journey

Once you have the experience the actual building work can be fairly straight forward, but Mike feels it’s important to maintain good communication throughout. The best jobs also tend to be where there is good communication with the architect and collaborative working from the outset.

Selecting a builder through a tender is not ideal

A lot of architects who deal with Passivhaus realise that the collaborative method of working is better, and appoint a contractor very early on. They can try and work out the price with them, do the detailing together and make sure everyone understands what’s going on.

Mike feels that if you were to put a job out to tender you couldn’t be sure that the person that wins has an understanding of what they need to do.

Mike says that a lot of committed Passivhaus builders are doing jobs quite competitively, and it’s important to remember that you could easily be doing a Passivhaus for less than another builder would be quoting to do a similar traditional house to a high standard. He reminds us that typically a Passivhaus might cost around 10% more, but by definition it’s a high quality house.

“Even if it’s 10% more, it’s 10 times as good!”

Vowchurch – photo by George Mikurcik

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February 17, 2016
HPH111 : How value engineering could benefit a house build – with Nick Grant from Elemental Solutions
Nick Grant of Elemental Solutions explains what is meant by value engineering and how it can be used in the house building process.

Interview with Nick Grant

Nick was a Trustee of the AECB and is Technical Director of the Passivhaus Trust. He is a sustainable building consultant with a background in engineering and, stemming from a childhood ‘make do and mend’ mentality, a lifelong passion for doing more with less.

Giving maximum value through engineering

As an engineer, one of the modules that most inspired Nick was one about value engineering.

Value is defined by Nick as being performance divided by cost. If you maximise performance, or reduce cost, it increases value.

Nick cites as an example the trend of smartphones having fewer buttons than ever before. An iPhone has been very value engineered in that “it manages to deliver a lot by doing very little and it takes a lot of effort to get to that”.

In engineering it’s an incredibly positive thing and what is strived for, however when Nick started working in the construction industry he discovered that people were using the term to mean cost-cutting in a negative sense:

“So I went from this thing being something I thought was inherently a great thing and a real challenge and exciting, and for me defined really good design, to this thing that people say “it’s been value engineered, they’ve ruined my project, they value engineered it.”

Value engineering has to happen at the beginning of a project

It needs to happen right at the start when the design is being developed. Decisions about the size, shape, orientation, etc all have an impact on the final value, cost and challenges that are going to arise. If the correct steps haven’t been taken at the beginning then it is likely that contracts in the tender will come back over budget, resulting in a cost-cutting exercise which will inevitably see the removal of features that you liked about the design.

Dempsey Decourcy Architects – Vowchurch

It should be integrated in the house building process

Nick feels that everything he does is value engineering, but that people can be reluctant to pay for something which leaves them feeling like they’re actually getting less. It may be that they’ve been told about something which they didn’t need to do, thus saving money, but they haven’t actually got anything tangible for it.

Typically in architecture it tends to be cost cutting and might be carried out by a Quantity Surveyor. Nick feels however that it should be completely integrated, with everyone on board and led by the lead designer. There should be encouragement, whether for the structural engineer, landscape architect, energy consultant etc, to find better, cheaper and easier ways of doing things.

Example of VE interior detail – polished concrete floor / foundations

Example of VE interior detail – Kitchen cupboards made of shuttering ply and surplus stainless steel washers

Having constraints on a project can be a positive

Nick says that rather than having to make compromises if they’ve run out of time or budget, it should be the case that if the correct work has been put in during the process they should be able to come to something “where it kind of all works.”

Having constraints can in some ways make the job easier. There can be fewer choices needing to be made and subsequently less things that they can get wrong. It can free the designer to focus on other things as well.

“So the more constraints we have, I think as a designer I take that as, I like that. So if we’ve got a very small budget, limited palate of materials, I quite like the challenge of that.”

By establishing a budget early on you can immediately realise that there are things that might not need to be considered, such as the indoor swimming pool and fancy finishes!

Dempsey Decourcy Architects – Cae Duff

“So you’ve got to do the value engineering, you’ve got to find a better way of doing things, find more clever materials, but you’ve got to also set a budget and then work to that budget. Otherwise everything will just expand to meet it.”

You can do things cheaply, quickly or well: you can’t do all three!

Nick and his partner designed and built their own home, blowing their original £30,000 budget and spending £40,000! While they like to think they did it well and cheaply, it did take them a long time to complete. They took inspiration from Christopher Alexander’s book A Pattern Language, but by doing that they did end up with a house that has a very complex form (a form factor of around 5) and which was a lot more time consuming to build.

It’s not easy to do simple!

By working on repeat projects Nick has been able to invest the time into working out details that appear to be simple, but if they were that easy everyone would be doing them! The process can evolve very slowly but benefits are reaped by the experience gained, thus making things easier on the next projects.

Dempsey Decourcy Architects – Cae Duff

Give a great deal of thought about the number and function of windows being used

Nick is currently doing some work on overheating for the Passivhaus Trust. He explains that in our climate we tend to want to let the sunlight in and aren’t used to going out and putting the shutters down, whereas in warmer climes this is something people do automatically. It therefore shouldn’t be a surprise when we return home and find them overheating!

So firstly it’s important to have enough glass for views and letting daylight in, but without having too much.

Glazing is expensive so, coming back to value engineering, make the window do as much work for you as possible. Thinking of function, if there are windows that can’t easily be accessed and opened, then consider a fixed rather than openable one, which typically you could pay 30% less for.

Nick gives this example of his own window behind the kitchen sink which they can’t easily reach to open, and suggests that actually a fixed, single frame view would probably have been better.

Have a guess what percentage of glass there is to frame, and find out the answer in the podcast. The answer may surprise you!

Ensure also that if your windows are to open, that they open enough to get the airflows. Often they open in a restricted reveal which doesn’t allow enough air in. Evolving over many buildings, Nick has learned to step the reveals in a way that when the window is tilted it still allows good airflow. It’s this repetition, and going back to review previous jobs, that is critical to learning and making improvements next time.

Decide what matters and work to your budget

Deciding what matters and working to your budget is Nick’s key piece of advice.

“Everything isn’t possible. But again that shouldn’t mean there’s a compromise necessarily. What you end up with you shouldn’t be thinking oh I really miss the little Victorian fake windows, you should think oh thank God I didn’t do that!”

Find out more

Follow Nick Grant on Twitter

Find out more about Elemental Solutions

View Nick’s presentation: Value Engineering, What’s not to love?

Find out more about Charles Grylls and Dempsey Decourcy Architects

Transcript

Download a transcript of the interview with Nick Grant.

Inquiry into the Quality of New Build Housing in England

Towards the end of last year, Ben was part of a panel at the Inquiry into the Quality of New Build Housing in England, at the Houses of Parliament. Presenting to a handful of politicians and construction professionals, those contributing included:
- Phil Waller, who has previously worked for a major house builder. His opinion was that they could be doing much better, and he has set up a website to try and advise potential purchasers what they should be looking for if they’re intending to buy from a developer.
- Geoff Peter from Wingrove Law is a solicitor who represents owners of new builds who have ongoing issues with their homes.
We know what a lot of the issues are and a lot of good questions were being asked, but it just comes down to whether anything will actually get done.

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January 13, 2016
HPH097 :What Do You Get for Passivhaus Certification? – with Peter Warm from WARM

Peter Warm from WARM: Low Energy Building Practice explains why building to Passivhaus standard is desirable, how certification comes into the equation, and what steps will increase your chances of reaching certification.

Interview with Peter Warm

Peter has been an energy engineer all his working life and is fascinated by high performance buildings. Through his involvement with the AECB he got into Passivhaus certification, and this is now a key service offered at WARM: Low Energy Building Practice.

“Glass Boxes are a Huge Problem”

One of the biggest challenges WARM face is communicating to architects that vast quantities of glazing in a Passivhaus actually create a “solar cooker”. While the glazing is expensive it also creates a problem which will need remedying with the additional cost of solar shading.

“Glass boxes” are effectively huge energy consumers, either for heating or cooling.

Passivhaus Certification is a Form of Training for Designers

Peter thinks of the certification process as a form of training because it gives designers a deeper understanding of how the decisions they make impact on the energy performance of their buildings.

If the designer hasn’t reached the Passivhaus standard before then inevitably there is a learning curve. However, the certification process provides support throughout, in order to iron out any issues before they occur.

For designers that WARM have worked with many times before they will be offered a greatly reduced quote because they need far less hand-holding throughout the process. In these cases, it’s really all about the documentation.

“Passivhaus Certification…It’s Just About Building Buildings Sensibly, Doing it Properly”

Peter suspects that in 20 years time the current quality of a Passivhaus will be the norm for a new build. Although much of the UK construction market is currently lagging far behind in terms of build quality and low energy standards, Peter sees retrofits as being a greater challenge for the future. There needs to be more education about the dangers of getting insulation wrong which – if not done properly – can cause mould, condensation and rot as well which in turn can impact on the occupants’ health.

The Steps to Certification

The Quote – This is based on the plans and sketches, an idea of how long the process is going to take and the level of support the designer is likely to need.

Design Review – It is important to review the designs before planning to look at the impact of things like the form factor (on insulation and airtightness) and fenestration (on solar gains).

Checks Before Going On-Site – WARM will usually do their own PHPP calculations to check thermal bridging, airtightness, heating, ventilation, etc.

On-Site Checks – This doesn’t usually apply to small projects. On large ones there can be a high turnover of tradespeople so the checks are helpful in identifying any problems at the time.

The Air Test – Along with the air test they check the commissioning report for the MVHR and make sure the system is working properly and quietly. If they’re happy with everything the information is sent to Germany for the authorisation to issue the certificate.

Reasons Why Buildings Fail Certification

Airtightness – Failing to test while there is still access to the airtightness layer can be a big issue in one-off houses. This needs the doors and windows to be put in at an earlier stage than a builder would normally like.

Building Services – This usually applies more in larger buildings. In particular it is poorly designed or installed ventilation units. When this happens the fan has to work harder which means greater noise.

Not Consulting Throughout – Less common is when people just build their buildings and then approach WARM for certification once it’s complete. In this instance it is likely they will not reach the standard.

As Passivhaus is about the comfort of the occupants, failing certification will mean that it may not be as comfortable as they would like, perhaps living with draughts and MVHR noise. Peter says: “Comfort is one of those strange things where, if you notice it, it’s not comfortable.”

Airtightness was the Biggest Challenge for WARM’s Own Office Retrofit

Built in the 1960s, they have transformed a draughty first floor flat into an EnerPHit standard office.

They achieved this by insulating externally, filling the cavity, insulating between the office and the shop, and putting in roof insulation at rafter level.

Deciding where the airtightness layer was going to go was the biggest challenge, particularly as the shop below was not part of the retrofit.

All the windows were also replaced with high performance triple-glazed windows and an MVHR system was installed.

Inevitably Building Regulations will Catch Up with the Passivhaus Standard

Peter considers Passivhaus as being such common sense that he believes it is inevitable that regulations will eventually meet the standard. With building regulations changing every few years to require more insulation for example, by choosing Passivhaus now your project won’t date.

Peter says: “It will happen. You’re just making it happen a little earlier.”

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September 2, 2015
HPH020 : An Introduction to Ventilation in The Home – with Andy Simmonds from Simmonds Mills Architects
Andy Simmonds from Simmonds Mills Architects explains ventilation in the home, why it’s important and what the options are if you’re looking to retrofit a property for energy efficiency.

Interview with Andy Simmonds

Aged 12, Andy got his first taste of sustainable construction taking a few courses at the Centre for Alternative Technology. After attending architecture college, Andy worked with engineer Chris Wallis, son of Barnes Wallis, on numerous interesting projects including stonework, timber frame construction, repairing windmills, etc. With a love of nature and the countryside, he developed an awareness of the importance of ecology when designing and building. As well as running Simmonds Mills Architects he is part time Chief Executive of the AECB (the sustainable building association).

The AECB is a Network of People with a Common Aim of Promoting Sustainable Building

Andy gives some background about the AECB. It was set up by a builder and his wife in 1989, focussing on construction but with an awareness of ecology and the environment. It’s got a very broad mix of members and there are many resources, such as the low energy buildings database, the technical discussion forums, the annual conference, local groups and so on. With about 1500 members, this vibrant group of people share their practical experience and expertise with each other. Andy says it’s a very fast way of learning, getting to grips with things and improving your business as well.

Ventilation is Necessary to Get The Air to Breathe, But Also to Remove The Pollutants

Andy uses an example of the International Space Station to illustrate the fundamentals of ventilation. They are in a sealed unit (although not completely airtight) and need air to breathe, but also a way to flush away pollutants. These could be carbon dioxide or other gases created by equipment, etc.

Early Buildings Just Let The Wind Blow Through

Although early buildings had a lot of natural ventilation, some stone and brick buildings with solid floors were actually pretty airtight. As people found new ways of building, some constructions (from 60s, 70s and 80s, for example) were potentially leakier and more open to the elements than some of the older buildings. Draught proofing without thinking of ventilation can create quite unhealthy environments.

Over Ventilating and Under Ventilating Are The Two Extremes

A house with all its windows open could be an example of over ventilating. This might be useful to clear a fug but if it’s cold outside, a lot of heat energy from the house will be wasted during ventilation. The reverse situation could be keeping all the windows shut and draught proofing well, so any pollutants from off-gassing carpets (for example) or from cooking with gas hob, etc., cannot escape. In the heating season neither of these extremes is an effective way of ventilating a house and getting good air quality.

In a Retrofit, Mechanical Ventilation Lets You Control The Situation

Mechanical ventilation is an approach that’s becoming used much more often. Two systems worth considering at are extract-only or mechanical ventilation with heat recovery (MVHR).

Extract-only Mechanical Ventilation

This approach extracts air from wet rooms, kitchens, bathrooms and so on, and then the fresh air is drawn in through trickle vents in the windows. These are slots in the windows, which will provide a background level of fresh air coming into the house. However, with the extract ventilation system, which is basically a box with a fan in it, the air is continually pulled through at a very low level. Even with a peak load during cooking, for example, this background ventilation can cope without turning up the fan.

Incoming Air From Trickle Vents Will be at The Outdoor Temperature

Andy explains that on a cold winter’s day, you might feel that incoming air as a cold draught if you’re sitting near the window. This is why radiators have often been positioned underneath the windows, so as the cold air comes in it falls down and to some extent warms up. Andy outlines a good approach used in Scandinavia, where they put an air inlet through the wall, maybe behind the radiator, so as you pull in air from outside it comes and warms itself on the radiator and doesn’t feel like chilled air.

Mechanical Ventilation with Heat Recovery Provides Fresh Air and Keeps The Heat

Mechanical ventilation with heat recovery both extracts the air from the wet rooms (kitchens, bathrooms and so on) but also puts it back in via ducts and air terminals throughout the house. This is therefore a balanced system. Although the heat is taken out of the outgoing air and put back into the incoming air, the air itself doesn’t mix. The heat is transferred as the air crosses through a matrix, a plastic honeycomb for example. So just the heat is transferred. The warmed incoming air is fresh.

In a Low Energy Retrofit, Ventilation Air and Air Leakage are Considered Separate Issues

Andy points out that until recently ‘ventilation air’ and ‘air leakage’ (the air that finds its way in through cracks, gaps and holes in the building) were much the same thing. However, in a low energy retrofit where the objective is to make the building as airtight as possible, the issues are considered separately. Creating and designing a system specifically for ventilation is vital.

Think About Ventilation From The Outset

Your ventilation strategy will depend a lot on the building you’re hoping to retrofit. Once you have a professional assessment of how airtight you can make the building, then you can make an appropriate strategy. British houses from the 1970s and 1980s can be difficult to make airtight, whereas solid-walled properties with solid floors are often much easier. This year the AECB aims to release a retrofit guidance programme to help in this process.

Grove Cottage meets the EnerPHit standard

Larger MVHR Units Are More Efficient

Andy talks through the MVHR unit he has at Grove Cottage, which has two low voltage, low wattage fans, one for extracting air from the house and one for pulling air into the house. The largest part of the box is the heat exchanger. Andy’s unit is situated behind cupboard doors in a utility room. While it does take up a fair amount of space, Andy points out that the larger the unit, the more efficient. This is because the more space the air has to move through, the less work the fans have to do, so very small units tend to be much less efficient than Passivhaus certified units.

Mechanical Ventilation Only Makes Sense With Certain Levels of Airtightness

Andy generally only recommends mechanical ventilation with heat recovery when the air change rate for the house is less than 1.5 air changes per hour. This is because the savings must warrant the investment in electrical energy. However, for the extract-only system an air change rate of 3 would be acceptable. Part of the difficulty is in planning for the air change rate when you’re deciding what sort of ventilation system to have, because after construction you may not have achieved the level of airtightness you had hoped for!

Externally Insulating Grove Cottage Was an Easy Route

Andy explains his approach to retrofitting Grove Cottage, which is a solid brick house. As the brickwork was of no particular architectural quality – it was painted white – externally insulating was the easier option (compared to internally insulating). The starting point was to mark on the plans in a red pen where the continuous air tightness plane goes, forming a strategy of how to deal with weak points. Andy describes how he sealed the brickwork to the roof membrane (which is basically a plastic sheet) with bitumen tape, which proved to be very successful. He emphasises the importance of a clear strategy and not leaving it to the last minute.

The Right Advice Can Save You Money

It is essential to spend time early on thinking through the detail of the retrofit. This could stop all sorts of problems arising on site and prevent a poor result at the end of the job. Andy reflects on how people can be reluctant to spend money on these services, preferring to invest in the measures instead. However, this upfront thinking could actually save a lot of money.

Maintaining a Ventilation System is Not Onerous

Andy’s MVHR unit runs throughout the year and supplies fresh air which is slightly warmed by the outgoing air (although it’s not a heating system) to about 21 degrees. The system has been set so that the fans go up to a higher speed around mealtimes, etc. While you can adjust it manually on the control panel as required, most of the time no intervention is necessary. The one exception to this is when the cardboard and fleece filters need changing. A light on the unit may even indicate when to do this.

Make Sure You Have Easy Access to Your Ventilation Unit

Think carefully about where the ventilation system is located. If it’s positioned in the loft or screwed down behind a panel, this will make the simple maintenance jobs more of a pain. Equally, in a retrofitted house like Grove Cottage (that has been well-insulated and has triple glazing, etc.) and is therefore peaceful, you want to locate the ventilation units away from quiet spaces. There will be a slight hum, so keep it away from sleeping areas, for example.

Ventilation Systems Must be Properly Commissioned and Balanced

When these systems are put in, it’s very important that they are commissioned and balanced properly. There’s a number of reasons for that, but in terms of comfort, over ventilation could mean that you start to notice draughts!

Not Considering Ventilation Could be a Health Risk

Andy outlines his concerns about the choices some people are making with their homes. He gives an example of putting in a wood stove. Leaving aside the combustion products and air pollution, Andy suggests that without an external air supply vent for the wood stove, you will be pulling in cold air up through your basement, through the floorboards and cracks and gaps. This will create cold draughts, which will add to discomfort, but the whole reason the stove was installed was to be more comfortable!

MVHR Systems For Retrofit Likely to be a Small Niche

Andy believes that we need to be much more conscious of ventilation because air quality is very important. He sees mechanical ventilation with heat recovery as being a relatively small niche for retrofit, but that extract-only ventilation could have a bigger role to play.

Useful Links

Download a PDF About Retrofitting Grove Cottage

Simmonds Mills Architects

Follow Andy Simmonds on Twitter

Transcript

Download a transcript of the interview with Andy Simmonds.

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April 10, 2013