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  • HPH271 : Common questions about the Passivhaus standard – with Ben Adam-Smith

    HPH271 : Common questions about the Passivhaus standard – with Ben Adam-Smith

    Ben Adam-Smith shares some of the questions that got asked about the Passivhaus standard during a question and answer session at the National Self Build & Renovation Centre.

    Passivhaus workshops

    Twice a year the National Self Build & Renovation Centre (NSBRC) hold a Passivhaus workshop in association with the Passivhaus Trust. This explains everything from the origins and principles of the standard to the benefits and how you might go about building your own Passivhaus.

    The event is hosted by Passivhaus Trust members who are also exhibitors at the NSBRC.

    Chairing the Q & A was Green Building Store’s Director Chris Herring

    The panel was slightly different each day but included Alan Budden from Eco Design Consultants, Jae Cotterell and Anna Carton from Passivhaus Homes, Paul Smith from Green Building Store, Jasper Meade from PYC Insulation, Robin Miller from Beco Wallform, Clarissa Youden and Michael Hunt Total Home Environment and self-builder Juraj Mikurcik.

    Before the Q & A began, Chris Herring asked the panel to give their top tip for building to Passivhaus standard.

    1. Put Passivhaus on the brief from day one
    2. Take a fabric first approach, investing your money in achieving Passivhaus standard before you even think about renewables
    3. Get buy in from all your team
    4. Make sure you hire someone with Passivhaus experience
    5. Don’t skip steps, like missing out the PHPP modelling
    6. Get the form factor down
    7. Keep it simple (and it will be easier and cheaper to achieve the Passivhaus standard)
    8. Design out the overheating risk
    A slide on why you don’t want to cut corners

    How do you heat a Passivhaus?

    There was no definitive answer for this.

    But first, a variation…

    “I’ve heard you don’t really need heating in a Passivhaus. Is that true?”

    This is a bit easier. Yes, you do need additional heat in a Passivhaus but it will only be a small amount of heat.

    If you’re going with renewables, an air source heat pump can be a good solution. Ground source heat pumps are generally overkill and therefore unlikely to be used.

    My own Passivhaus uses a gas boiler and although these are clearly on the way out, the gas main may still exist in some capacity in the future. So our logic was to connect now and then we can always dump that connection at a later date. And it’s much easier to do this than trying to connect at a later date. It’s also useful for resale purposes.

    Some of the panel suggested, as the grid decarbonises, that electric is the way to go. Jasper Meade talked about building their Passivhaus office with no heating at all and testing it for a couple of years. With a couple of electric heaters downstairs the whole building quickly reaches temperature in winter.

    Alan Budden followed a similar logic, saying that electric panel heaters could be good. And they’re portable too.

    The stove at The Deerings

    What do you think about having a wood burning stove in a Passivhaus?

    While this is possible, it’s a good question to ask why you want this. Is it because all your other houses have had one?! Maybe you’ve been huddled around the fire in the winter. Well the experience of living in a Passivhaus is going to be quite different.

    The other thing to remember is, no matter how sealed the system, when you add your fuel the stoves will give off particulates. So there are health risks attached.

    But if you do still want a wood-burner (perhaps you have your own supply of wood) make sure it has its own air supply.

    Is thermal mass important in a Passivhaus?

    The panel agreed that having some thermal storage capacity was a good idea, but it doesn’t have to be a lot. This has the effect of just smoothing out the temperature, particularly in summer.

    And interestingly, some build systems might have more thermal mass than you think. While concrete is often cited, Jae Cotterell talked about the PH15 timber frame system having significant thermal mass in the form of the cellulose insulation!

    What is the value of certification?

    This is about quality assurance and is particularly important when your team has limited experience of achieving Passivhaus standard.

    If a company has built lots of certified units before, they probably could deliver a Passivhaus with little trouble and the certification may be less important. However, if hiring someone with less experience, following the principles will not necessarily get you to Passivhaus standard.

    So certification may just seem like a badge but there is a whole process behind it.

    The other aspect to bear in mind is resale. Those looking to buy a Passivhaus are likely to want a certified property rather than taking homeowner’s word that they’ve built a Passivhaus.

    It’s also worth remembering that you can get certification at a later date; just make sure you gather all the necessary documentation at the time of the design and build.

    Can you make a Victorian house into a Passivhaus?

    Yes, this is entirely possible (such as Tom Pakenham’s retrofit).

    However, it’s not straightforward, you’re making the building do something it wasn’t designed to do and it won’t be cheap.

    Even the Passivhaus retrofit standard EnerPHit is still a challenge. It’s slightly less stringent but still demanding.

    We’ve covered various different retrofits on the podcast including Harry Paticas’s phased retrofit of a town house.

    Harry Paticas and his son in their retrofitted home

    We’ve got a plot, what are the first steps to designing a Passivhaus?

    • Put it on your brief and go in search of professionals who have done it before (check that someone on the team is a certified Passivhaus designer).
    • Read the guidance on the Passivhaus Trust website.
    • Visit Passivhaus properties as part of the International Passivhaus Open Days. Quiz the owners about their own experience and the team they hired.
    • Get familiar with the requirements of the Passivhaus standard so that you can make good decisions (and avoid complicating it and adding extra costs).
    The PH15 system from Passivhaus Homes

    Does the Passivhaus standard take you down a timber frame route?

    Passivhaus can be achieved with any build system. You could make an argument that insulated concrete formwork (ICF) makes the airtightness easy while a masonry approach involves putting together a big jigsaw… but fundamentally you can reach Passivhaus standard with any construction system.

    But the choice of build system comes down to personal preference and takes into account a number of factors such as cost, ecological criteria, ease of assembly, and so on.

    When it comes to planning, how easy is it to adjust the orientation of a house?

    As with anything connected to UK planning, it can boil down to the local authority. Some are better than others!

    However, most authorities can see the benefit of having more Passivhaus buildings and understand the need to optimise the orientation.

    Find out more

    The National Self Build & Renovation Centre

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  • HPH124 : A contemporary Passivhaus home, built with SIPs – with Paul Newman from Potton

    HPH124 : A contemporary Passivhaus home, built with SIPs – with Paul Newman from Potton

    Paul Newman from Potton talks through the construction of the UK’s first Passivhaus show home.

     

    Interview with Paul Newman

    Paul Newman is the Self Build Director at Potton. Potton, which recently celebrated their 50th anniversary, have helped design and build over 6000 homes and have a portfolio of over 12,000 different designs. The Potton approach to custom build is to work with landowners to secure outline planning permission on their sites, with design left as a reserved matter. They find customers for those sites who then buy the land from the individual landowners. Potton then work with the customers to provide their normal self build package.

    At their site in St Neots they have a show centre of completed houses, where they are currently adding a Passivhaus. They have been sharing progress of this build with video updates and have also allowed members of the public to experience it being built.

    Potton Passivhaus mock up

     

    Building a Passivhaus show home was an obvious step

    Potton have four complete show homes at their St Neots site and one at the National Self Build and Renovation Centre. Moving with the changing market and increased demand for low energy homes, their last show house was constructed to achieve level 4 of the Code for Sustainable Homes. Wanting to move their business on and offer customers something new, they decided to construct a further show house, with a Passivhaus being the obvious choice.

    Their experience over the last 8 years has been that they’re being asked more and more often about energy efficiency and low energy homes and hope that this Passivhaus and the lessons they have learnt from it will put them in good stead for the future.

     


     

    The design aimed to push the Passivhaus standard hard!

    In coming up with the design Potton were keen to challenge the reputation that Passivhaus buildings sometimes have of being simple, boxy designs. They expect to evolve different design forms based on this Passivhaus, while not necessarily directly repeating it.

    They worked with HTA Design, an external design consultancy, on the plans, and also had specialist help from Passivhaus experts WARM.

    The building form is quite complicated and has a valley roof, so from a thermal bridging perspective the junctions have been tricky to resolve. Paul also thinks their life would have been much easier if they’d taken 18 inches of height off the design!

    Potton Passivhaus cross section

    Something they found encouraging was the use of an innovative self adhesive breathable membrane which has contributed positively to the building’s airtightness. The first airtightness test had a figure of 0.68 but after some alterations they managed to get it down to 0.5.

     

    The SIPs system took a matter of days to install

    The house has been constructed with Kingspan Tek – a product which is certified by the Passivhaus Institute – and Potton have been using it for the last 10 years on both their self build and volume contracting business. It provides a thermally robust solution and can be erected on site very quickly. One consideration, however, is that once installed it is hard to make changes to room layouts, etc.

     


     

    Use PHPP modelling from day one to see how the building is performing

    Paul explains that early modelling in the Passivhaus Planning Package was an important lesson for them when designing the Passivhaus. By doing this, something that showed up early on was that the building had a tendency more than was desirable to overheat. They were able to experiment by changing the overhangs, reveal depths and specification of the performance of the glazed units within the windows to make a considerable difference.

     

    Engage with suppliers early in the process

    There are two main lessons that Paul feels they have learned from the Passivhaus self build process. The first is the need to engage early on with suppliers to make sure they understand what you’re trying to achieve, have the right products available and certifications in place where appropriate. While they did try and engage early with their supply chain, their lesson was that they actually should have engaged even earlier and placed some of their orders earlier too.

    Secondly, Potton worked with sub-contractors who they have used on hundreds of other Potton houses in the past. What they found was more attention to detail was required to achieve Passivhaus performance, and they needed to have their hands held tightly throughout. Paul thinks this is something that won’t be unique to their build, as there just aren’t enough experienced Passivhaus sub-contractors out there.

     

    Find out more

    Visit the Potton website

    Find out more about Potton’s Self Build Academy

    Find out more about Potton’s Self Build Live

    Follow Potton on Twitter

     

     

    Transcript

    Download a transcript of the interview with Paul Newman.

     

    The Hub update

    Our Getting Started module is for absolute beginners who want to know how to research a house build. We’ve laid out a logical route so you can get going.

    In the Long Barrow case study the latest video shows the steel frame going up, and explains the areas where they needed to be careful of thermal bridging as they wanted to attach a balcony and a brise soleil as well.

    Elements of The Hub are free to view, but for full access the price currently is just £45 for the year.

     

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  • HPH120 : What is a self build mortgage? – with Thomas Honour of BuildStore

    HPH120 : What is a self build mortgage? – with Thomas Honour of BuildStore

    Thomas Honour, mortgage adviser at BuildStore, explains the self build mortgage process.

    Tom Honour (2)

     

    Interview with Thomas Honour

    In this interview we’ve returned to the National Self Build and Renovation Centre (NSBRC), this time to chat with Thomas Honour who works as an adviser with BuildStore mortgage services. BuildStore specialise in finance for projects, so self builds, custom builds, renovations etc. They have had a presence at the NSBRC since it opened, with a permanent base there for mortgage advisers who also contribute to the seminars on finance.

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    Consult a mortgage adviser at an early stage

    This will help you to ascertain your borrowing capacity and determine whether your budget for the plot and build is is likely to be realistic.

    Salary is the single most important factor in determining available finance, but other considerations will include things like ongoing credit commitments, childcare costs and any other significant outgoings.

    Each lender is very different but typically they will apply an income multiplier of between 4 and 4.25 times the joint household income, with some treating bonus and overtime payments differently.

     

    There are two different types of self build mortgage product

    The main difference between a self build mortgage and a conventional mortgage is the way in which the funds are released. With a conventional mortgage you receive the funds in a lump sum, which together with your deposit, you use to purchase the property.

    With self build mortgages the money is released typically in four or five stages, over two phases. The first phase is releasing money to purchase the plot and the second phase releases money to finance the build.

    The traditional self build product provides money in arrears of the stage being completed. This works well for people that have larger deposits or who own the land, as they are putting in their own money upfront with the lender giving the money in arrears on completion.

    Construction types such as insulated concrete formwork (ICF), structurally insulated panels (SIPs) and timber frame however often require a much larger payment to the manufacturer early in the project. BuildStore have designed their “Accelerator” product to mitigate these cash flow difficulties by giving the money in advance of each stage.

     

    Your mortgage broker has a duty of care to ensure your mortgage is affordable to you

    The mortgage broker and lender will work together to ensure that your build costs are reasonable and that they’re going to be plausible for the type of project that you are doing. This aims to prevent the need for anyone to return mid-project requesting more funds, with no guarantee they will be provided, and will likely cause delays.

    On rare occasions people do return requesting additional funds. An additional loan known as a “further advance” or “additional advance” can be applied for to make sure that the build can be completed, subject to underwriting from the lender.

    It’s important that budgets are broken down in detail. Sometimes people may not have considered contingencies and additional expenses such as architect fees, stamp duty on land, site insurance and structural warranties. A mortgage broker would rather decline an application upfront than put them in a position where they have a project they can’t complete because they don’t have enough money.

    It is worth bearing in mind that most lenders will have some sort of caveat that the build must be completed within two years.

    Since the mortgage market review by the regulator a couple of years ago there is a greater burden on the lender to ensure they are lending responsibly. While Thomas believes that this is right and should be the case, some of their affordability criteria does limit the amount that people can borrow which means they may need to put more down as a deposit.

    Buildstore015

     

    There are costs to setting up a self build mortgage

    This will vary from lender to lender but as with standard mortgages there will be costs to get it set up. These may include:

    • An arrangement fee – most lenders will charge this as standard on any type of mortgage
    • Valuation fee – this will value the plot based on its value at the time and what you’re paying for it. They will also give an end value based on what you’re planning to build and what they think it will be worth when completed. There is also a reinstatement value for site insurance purposes.
    • Additional fees – some lenders may charge booking fees which are all quite similar but may be named differently.

    The job of your broker is to ensure you’re aware of all the fees upfront to know what they are, what they cover, what they’re costing you and when they’re due.

     

    A bridging facility may be suitable for people that have assets but a low income

    Thomas uses the example of someone with a house worth £500,000 but a pension income of £10,000, but wanting to borrow more than a typical mortgage would allow them on that income.

    Potentially there can be bridging finance secured against the existing home which would enable them to build their house. Money from the sale of their old home can then pay off the bridging facility.

     

    Not all lenders will lend on all construction types

    Non-standard constructions can be funded, however “non-standard” means different things to different lenders, so your mortgage broker will find a lender that is suitable for your project. Even timber frame, steel frame, SIPs and ICF constructions are considered non-standard by some lenders.

    The reason why some lenders won’t lend on less traditional buildings is largely down to re-saleability. The lender is always thinking about if they had to take possession of the property how easy it would be to sell. For properties that might be an acquired taste they will be worried they may not get their money back.

     

    The larger the deposit, the more favourable the interest rates

    Typically the minimum deposit required will be around 10% of the overall project costs. The project cost is the combined land and build costs.

    For someone that already owns the land outright, the value of the plot can be used as the deposit contribution, i.e. owning a plot with a value of £50,000 will provide £50,000 towards the deposit.

    A larger deposit will give more favourable interest rates and may make more lenders available to you.

    BuildStore

     

    Find out more

    Visit the BuildStore website

    Follow BuildStore on Twitter

     

    Transcript

    Download a transcript of the interview with Thomas Honour.

     

    The Hub update

    We’d like to tell you a little bit about The Hub – what it is and why we’re doing it.

    Support: A self build project can be a long journey so the community side of The Hub is a place to learn from others and be inspired by them.

    Information: We’re already providing lots of information with our podcasts and videos on YouTube, but this is going a step further by trying to refine and organise it, making a step by step and easy to understand guide of what’s involved in a self build.

    Videos: There’s huge potential for learning by video and here at Regen Media it’s what we specialise in.

    As content creators and communicators, we can do much more, not only in The Hub, but also by adding free content and perhaps help other people to achieve more and spread their messages further. If we can save you time and money by making The Hub work, then hopefully you’re paying for a resource that you’re happy with and which is giving us more funds that we can use to create in other areas.

     

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  • HPH119 : Sourcing materials for your self build – with Harvey Fremlin from the National Self Build & Renovation Centre

    HPH119 : Sourcing materials for your self build – with Harvey Fremlin from the National Self Build & Renovation Centre

    Harvey Fremlin, Managing Director of the National Self Build and Renovation Centre, explains how to go about sourcing sustainable materials for your self build.

    Harvey Fremlin

     

    Interview with Harvey Fremlin

    In 2008, after working on a construction site, Harvey joined the team at the National Self Build and Renovation Centre (NSBRC). The centre is a permanent venue for independent advice and support and has exhibits, workshops and courses for people with an interest in self-building or renovating.

    Centre Blue Sky

    Neil Helpdesk

     

    “Don’t be afraid to big-up your project!”

    It is likely that at some stage of your project you’ll be buying materials from a builders merchant. They can be intimidating places if you’re not in the trade.

    Harvey says that some merchants are more self-builder friendly, so it’s worth shopping around and not being afraid to talk about your budget and how much you’ll likely be spending with them. That way you may be offered bigger discounts.

     

    Manufacturers and suppliers are increasingly happy to deal with consumers directly

    Harvey has found that suppliers and manufacturers are increasingly sending people with technical backgrounds to their shows, rather than sales people. This is because visitors are keen to know more than just what a system is and how it works. Instead they are asking questions about technical specifications, the advantages of one system over another, how to get maximum performance from the system and whether it is absolutely right for their project.

    Trade Village

     

    Fabric first – products later

    The mantra at the centre is “fabric first” – invest in the envelope of the building to reduce the energy demand before considering “shiny technologies” and renewables.

    Harvey stresses there is still a place for renewables and that the centre is a big advocate of them, but without thinking about the fabric and the building materials from the early stages of the project, they will be pointless.

    TV3

    Self-builders have a much longer term view on building their home, in comparison to a volume house builder:

    “They’re not necessarily just looking at the immediate cost of using a particular system or a particular technology, they’re considering the payback periods and what the long term benefits are of investing the money up front in terms of choosing those potentially slightly more expensive materials. But in the long term lifespan of that home there should be huge savings there.”

     

    Keep on top of availability of supplies

    It is important to consider availability, because depending on the lead times of products you could end up impacting on your whole building programme if you’re waiting for something to arrive.

    As well as keeping on top of when things are going to be delivered, bear in mind the stage at which your build will be when the next batch of supplies are going to be delivered, and whether there will be sufficient access.

    Cash flow will partly determine how much you can buy up front, but do consider storage of items – some are going to be bulky and need to be kept dry.

    “So if you can actually arrange for the products to arrive almost in a just in time scenario, so a day or two before you actually need them, it takes away an awful lot of headaches.”

     

    Keep your site and supplies secure

    If you have a lot of products on site you will need to keep your site secure, with adequate fencing and probably an alarm system. Most people will purchase site insurance and this will stipulate the security arrangements that will need to be in place.

     

    Do plenty of research before selecting your products

    Ultimately your choice of product will come down to individual preference. Ensure however you do lots of research, talking to companies, reading brochures, and comparing one product with another.

    Once you know the style you like, check that it will be permitted within your planning consent.

    As well as choosing your product according to style, cost and performance, you will also need to consider availability and whether the products you want are actually going to be available when you need them.

     

    Use your own judgement when selecting products according to their green credentials

    Harvey suggests being honest and asking yourself what you really mean when you say that you want to be sustainable. Is it because you’re genuinely concerned about climate change, or is it being worried about energy consumption and rising energy bills? Being clear about this can help shape your decisions about how you proceed to build.

    Harvey says that any company will argue that the products it is supplying are “green” and “eco”. But while there are companies that only deal with sustainable products, it is really down to you to decide what you feel is right for you.

     

    You can claim the VAT back on a self build

    If you are doing a self build project in the UK you can claim the VAT back, but this can only be done once. For this reason most people would usually leave it until the very end and the owner has moved in. For some people it can be a way of freeing up cash earlier in the project if budgets are tight, however they will not be able to claim again for subsequent purchases. Harvey’s tip is to ensure you keep every receipt carefully filed away throughout the build.

    TV4

     

    NSBRC course tutors are experienced self-builders

    First time visitors to the centre generally arrive full of inspiration and at the early stages of a project. Often they will return a few months later with different mindsets, where they’re focusing on the building systems and the materials that they might use. The courses the centre provides are generally aimed at first time self-builders, to give them plenty of information, advice and confidence.

    LT1

     

    Find out more

    NSBRC Logo

     

     

    Visit the NSBRC website

    Follow NSBRC on Twitter

     

    Transcript

    Download a transcript of the interview with Harvey Fremlin.

     

    The Hub update

    Our latest module covers insulation and airtightness, also touching on the Passivhaus standard. We’re looking at how you achieve high quality installation and the factors that are going to make a difference.

    There’s also another video in the Long Barrow Passivhaus story. They have finished the foundations and are building up the basement with insulated concrete formwork.

    By being a Hub member you can also join our closed Facebook group and network with fellow self-builders.

     

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