Contact →

Tag: energy effficiency

  • HPH332 : How accurate are Energy Performance Certificates (EPCs)? – with Tom Gwilliam

    HPH332 : How accurate are Energy Performance Certificates (EPCs)? – with Tom Gwilliam

    Tom Gwilliam explains what Energy Performance Certificates (EPCs) are, how they are created and why they are unlikely to be a useful measure of how energy efficient a building is.

    Interview with Tom Gwilliam

    Tom is a sustainability consultant at Etude, with a background in structural engineering, energy assessment and whole life carbon analysis. This episode was inspired by a previous episode, Should we celebrate architecture that performs poorly?, which relied heavily on EPC data.

    EPCs are a legal requirement when selling or renting a home

    Energy Performance Certificates give a rating between A and G, and a number between one and 100, of how energy efficient the home is. This is the main output, but there’s also other information about what you might do with the home and how the home is performing at the moment.

    A domestic energy assessor carries out a SAP assessment on new-builds, or an on-construction domestic energy assessor carries out a ‘reduced data’ SAP (RdSAP) assessment on an existing building. The two are different, but both rely on entering information into a computer model, which outputs the EPC.

    SAP assessments make assumptions about how a building operates

    SAP stands for the Standard Assessment Procedure. It measures heat loss, domestic hot water use, energy associated with pumps and fans, and the energy associated with lighting. It also estimates what people might use for appliances (‘unregulated energy’, because it varies by number of occupants and their behaviour).

    The assessment makes various assumptions and boils them down to a single number for total energy use in kilowatt hours. On top of that, it superimposes carbon emissions, primary energy, and other metrics used for building regulations compliance.

    EPCs also measure the cost of operating the building

    The EPC process takes the total energy figure and puts a cost on it for the resident. But the accuracy of that cost all depends on the accuracy of the assumptions made earlier in the calculation.

    SAP is used to drive policy decisions

    There’s an aspiration for every property in the UK to be at least EPC C by 2035. Part of the problem is that studies show the EPC rating doesn’t correlate well with the energy use of a building. You’d expect that moving from A to G would see increased energy use, but there isn’t much change in general.

    Even if all homes are a C by 2035, we’re unlikely to see much change in energy use in buildings. We’ll still have high energy homes and it will be too late in 2035. There’s a real incentivisation issue, and no strong grasp of how to improve buildings through the EPC process.

    Five different assessors would probably come up with five different EPCs

    Another major problem with EPCs is consistency – there is none. The EPC industry is not well-moderated, and assessors are paid quite poorly. Plus, there’s pressure at government level from house builders not to increase the cost of assessments and EPCs.

    The process relies on a person to interpret a physical characteristic of a building. People might measure things differently or inaccurately, or even completely wrong. Assessors also have to make a judgment on how old a building is, and how it’s constructed. They don’t have the time or money to investigate what’s actually in the walls, so a lot of their work is guessing and being as quick as they can.

    There’s proven evidence of getting an EPC for a new-build house, then sending an RdSAP assessor to do an assessment the next day, and the two producing completely different results.

    Example of an Energy Performance Certificate

    EPCs aren’t really about your home, even though they look like it

    An EPC is presented in a way that makes you think that it’s about your home, but it isn’t. If you had identical buildings in Cornwall and Durham, and carried out identical assessments, you’d get the same EPC. But we know the space heating demands for buildings in those two locations will be very different. That fundamentally undermines the EPC process.

    SAP doesn’t have the ‘as built’ check that Passivhaus does

    It’s possible to game the system, particularly with new-builds. SAP assessors don’t get paid well and they have to take the word of the developer or people on site. Assessors don’t have the required understanding of how a building is going to perform in reality. They don’t see all the detail, so they have to simplify things and make assumptions.

    When you have that disconnect between what’s happening in reality and what the computer model says, there’s a big incentive for developers to be unrealistic with what they’re saying. By contrast, two people carry out the Passivhaus process. There’s a designer and a certifier, and a peer review process going on all the time. It makes it a better-quality process.

    Simply adding a requirement for the SAP assessor to go to site at the end of construction would make a big difference.

    Thermal bridging is a particular issue

    Thermal bridging is a big source of heat loss in new-build properties. SAP has categories for thermal bridges, but they don’t cover everything. It’s hard to have a 3D understanding of a building when working off plans, so if you’re not on site and seeing where thermal bridges are occurring then they’re not getting picked up at all. There’s no way of quality checking that process because nobody is overseeing the SAP assessor.

    There are lots of assumptions about heating system performance

    The technology behind boilers and, in particular, heat pumps has lots of nuances. SAP doesn’t require the level of detail that influences whether heat pumps perform really efficiently or very poorly. The model doesn’t ask for a lot of information about the system, so it can only make a simplified judgement about how it will perform.

    A way to improve it would be to break the system down into more component parts, understand each part better, and reflect that in the calculation with evidence. If we’re going to shift to low carbon buildings, SAP assessments should reflect a need for more information and understanding to incentivise developers as part of the building regulations compliance process.

    Some people advocate for adopting Passivhaus

    It’s a proven system. With Passivhaus and PHPP, there’s a clear link between designed on-paper performance and in-use performance. It’s a tick box exercise in some ways: being detailed in how you assess the building, understanding what is built on site, and making sure that’s reflected in the calculation.

    Doing more testing would reduce cost for the whole industry

    We need to be able to survey our building stock at a level that gives us a better understanding of the energy performance of buildings, and not accept RdSAP as a minimum requirement. There is testing available, but it’s costly – and the only way to bring the cost down is to do more of it.

    You can’t judge a building’s quality by its EPC

    There is no information about indoor air quality, or other sustainability metrics. This is another area where Passivhaus excels. A Passivhaus is a good quality building that is pleasant to be in. We can’t tell from an EPC how good a building is going to be, so it’s impossible to compare one A-rated building to another A-rated building.

    Studies are highlighting the issues with EPCs

    Etude carried out a research project looking at EPCs versus metered energy use. And UCL Energy Institute has just published a paper looking at buildings they’ve been monitoring over a long period of time. The conclusions all come back to the issue of assumptions made in the SAP assessment.

    In addition, there are formulas within the SAP calculation that have been ‘locked in’ for years and they don’t change. The development of SAP over the last 20 years has been slow and it doesn’t reflect modern buildings. People know there’s an issue, but there’s no process for SAP to be regularly updated. When changes are proposed they have to be consulted on, so it’s all very slow.

    The Future Homes Standard is expected to change things

    Because people know there are issues, an overhaul of SAP is expected alongside introducing the Future Homes Standard in 2025. If SAP changes, that obviously changes how EPCs are generated. It’s not clear how the government would reconcile the difference between existing EPCs and the future EPC system.

    Home buyers can try to get hold of the SAP assessment behind the EPC…

    …but it requires a bit of knowledge in order to sense check it.

    • Make sure ventilation systems have been entered correctly.
    • If a default value has been used for thermal bridging, you could try and work out if that’s a fair assumption for your kind of building. Maybe ask on forums if it is a suitable way of measuring thermal bridging.
    • You could dig into the heating system and make sure what has been selected is what is actually in the building. Has the assessor selected all the right drop down boxes? Has a weather compensator been installed, for example.
    • Also look at what the assessment assumes for the occupancy of the building, because that drives a lot of energy use. You can see if it’s related to how many people are going to live in the building.

    If the numbers in the assessment don’t seem right then it’s up to you whether you appoint someone else to look at it. PHPP, or an open-source version of SAP, is available so it’s an option to try and do it yourself, if you want to.

    You’ll always need a SAP assessment because of building regulations…

    …but it’s interesting to do a PHPP calculation as well and compare the two. Etude has worked with local authorities to help them understand how SAP differs from reality.

    The local authority can’t mandate PHPP calculations, so Etude helps them to convert the SAP result to a more realistic number that can be measured against a policy target. The SAP inputs are still limited, but Etude can correct for known errors in the assessment.

    Getting EPC ratings wrong is a problem for retrofit policy

    Something needs to be done with RdSAP to make sure ratings are in line with what is expected for a building. As more homes are retrofitted, assessors will need to understand the age of the building, how it’s constructed, and where retrofit measures have already been put in place, in order to have confidence that improvements being made are actually going to make a material difference.

    Find out more

    Visit the website of Etude

    Check out the UCL Energy Institute’s research

    Download the Passivhaus Trust’s research report on EPCs

    Transcript

    Transcript of House Planning Help podcast – episode 332 (Tom Gwilliam)

    What are the UK Passivhaus Awards?

    If this award ceremony is not on your radar then you need to invest some time following the competition and delving into the archive. There have been some outstanding self build and retrofit projects in the hall of fame, so we recommend a lazy Sunday morning checking out the fact-files on the Passivhaus Trust website and watching some of the videos.

    Please connect with us

    Subscribe, rate and review us on Apple Podcasts

    Rate and review the podcast on Stitcher

    Like our Facebook page

    Follow us on Twitter

  • HPH196 : Why communication is central to self build success – with Lucy Pedler

    HPH196 : Why communication is central to self build success – with Lucy Pedler

    Lucy Pedler, architect and founder of The Green Register, talks about the importance of good communication throughout a self-build project.

    Interview with Lucy Pedler

    As a child, Lucy was interested in the worlds of science and arts and wanted a profession that could combine the two. She qualified 35 years ago, and has worked as an architect in the UK and US.

    Influenced by her father, an environmentalist, Lucy wanted her career to encompass both architectural and environmental work. In the early ‘90s, she worked as a Product Specialist at Construction Resources (the UK’s first Ecological Building Centre) for five years; this involved researching the environmental impact of building materials and systems, and training other construction professionals in green building.

    In 2000, Lucy launched The Green Register, a not-for-profit organisation providing independent training and promoting sustainable building practices across the construction industry.

    Poor communication is the cause of many problems

    Lucy believes we spend quite a lot of time as human beings not saying what we think! If you can communicate effectively – using a bit of tact and choosing words carefully – people know where they stand. Lucy says some people think she’s quite direct but at least there’s no grey area.

    Making the importance of communication clear from the start helps to create an environment where everybody’s comfortable talking about the build.

    A robust brief ensures everyone’s on the same page

    Good communication is key to making the project a success and this begins with a detailed brief. To produce one, the architect or designer must first thoroughly understand what the client wants.

    This document should then be referred to throughout the build process as things inevitably change. For example, there may be planning issues, unexpected problems on site, or design alterations. A detailed brief aids important discussions about the time, cost and design implications of changes.

    It’s worth spending time setting the green agenda

    When people tell Lucy they want a ‘low energy house’ she needs to clarify exactly what that means. Clients may just want low energy bills, or they may have concerns about the bigger picture: the way the house is built, materials used, internal environment, wellbeing, etc. It’s a lot of work that has to be done at the beginning, but Lucy says you’ll reap the benefits throughout the process.

    Be realistic about the budget from the outset

    A fabric first approach is much better in terms of environmental issues and impact. But Lucy understands that the majority of people don’t have the money to do 100% sustainable buildings, commenting, “Don’t beat yourself up if you haven’t got the perfect house because whatever you do is going to be better than the average house in the UK, which is very, very mediocre.”

    Lucy advises people to be honest about access to funds and what you have upfront. Then everybody involved knows what you can afford. You don’t want to run out of money and work to suddenly stop onsite.

    The project lead should manage expectations about cost

    During a career spanning more than 30 years, Lucy can’t remember a project where the cost didn’t change, usually in an upward direction. Managing clients’ expectations won’t make the problem go away, but lessens their disappointment.

    The architect (or lead) should explain the process and set expectations that the project will probably go over cost and time. If unexpected costs arise, they’ll refer back to the brief so the client can decide whether to increase the budget or save costs elsewhere. Lucy says self-builders often see the long-term benefits of increasing the budget.

    There’s huge value in face-to-face communication

    Modern communication technology sets expectations that everything can be done immediately. While some decisions are quick to make, Lucy thinks we’ve lost something in not being given the time to consider things.

    Projects can be discussed remotely using phone, Skype and email, but Lucy gives reasons why talking to clients in person can be advantageous:

    • You can sketch over plans while talking through concepts.
    • It’s easier to compare room sizes on plans with the room you’re all sitting in.
    • Some decisions take a bit of time and are best explained face-to-face.
    • You can observe non-verbal reactions, e.g. facial expressions.

    3D modelling makes it easier to convey concepts

    Many clients can’t understand 2D drawings and Lucy comments, “Why should they? It took us seven years of training to get where we are.” She recommends a programme called SketchUp, which is very simple and can quickly produce a 3D walkthrough to use with clients, helping them to experience light and height and changes in space, etc.

    It’s important that concepts aren’t presented as a fait accompli, and Lucy says clients should feel able to give feedback. Reviewing conceptual designs is a key stage for communication, when you’ll work out basics such as the position of the living room or the size of the kitchen.

    Design iterations take time and can be costly

    Lucy recalls a client who requested ten different designs for a 2m x 2m bathroom and chose the original one in the end! A helpful approach is for the architect or designer to state upfront the number of design options included in their price, and make it clear they’ll have to start charging extra for any additional major changes.

    A collaborative design and build approach is worth considering

    While in the States, Lucy worked with contractors from the conceptual stage onwards and the contractor would inform some of the technical decisions. This approach required a high level of trust, but meant shared ownership of the project. And when it came to pricing the job, the cost was quite realistic.

    Lucy says when you go out to competitive tender, contractors may not have understood the drawings or might not be pricing accurately. She cautions, “Although it might appear initially to be the lowest cost, at the end they’re clawing back what they need in order to make a profit.”

    A neutral third person can mediate between client and contractor

    Lucy says if clients can afford to appoint someone to oversee the project that’s a real plus. The architect or project manager can tell them early on what’s likely to happen during the construction stage and clarify what their fee will cover.

    Self-builders often get much more involved, but Lucy suggests clients don’t take on the project management role themselves as they’re too close to the project and usually don’t have the experience needed.

    Agree a schedule of meetings for the build

    When the construction stage begins, you’re introducing a lot more people, so communication can be challenging. And clients often perceive progress to be slow and see costs increase and timescales slip during this stage.

    It’s helpful to plan a schedule of meetings and clarify to the whole project team where they’ll be held, who does/doesn’t need to attend, what’s going to be covered, etc.

    Lucy says the one group of people they find very difficult to get into Green Register seminars are builders. She recommends ‘toolbox talks’ if you’re trying to achieve a low energy building, as spending just a few hours explaining the concepts is money well spent.

    3 more tips for a successful self-build

    1. The amount of information and decision-making can be overwhelming. Decide how involved you want to be, e.g. technical decisions may be best left to professionals trained to deal with them.
    2. It’s important no one in the team holds back. The client, architect or contractor needs to share their concerns or say if there’s something they have doubts about.
    3. The Green Register encourages post-occupancy monitoring (e.g. of airtightness, fuel costs, etc.). This can reassure you that you’ve got what you set out to achieve.

     

    Find out more

    Visit the website of The Green Register

    Follow The Green Register on Twitter

    Transcript

    Download a transcript of the interview with Lucy Pedler

    Please connect with me

  • HPH187 : What keeps a self-builder awake at night? – with Will Kirkman from Ecomerchant

    HPH187 : What keeps a self-builder awake at night? – with Will Kirkman from Ecomerchant

    Will Kirkman from Ecomerchant shares the key results of a survey the company ran to find out what self-builders worry about most.

    Interview with Will Kirkman

    Will didn’t actually get a PAYE job until his 40s. Assorted pursuits over the years, including farming and metalwork, eventually led him to civil engineering. He now runs Ecomerchant, a sustainable building materials supplier.

    Will says that self-building is a unique and new experience for most people who do it, so there can be a lot of uncertainty along the way.

    In an effort to find out a little bit more about the market, the company surveyed customers and identified the top five worries.

    1. How much should my project really cost?

    Total build cost is made up of many components. It can be hard to work out what proportion of the total should be on various upfront fees and professional services versus the construction itself, let alone establish actual costs. As dreams become reality, controlling costs can also prove tricky causing anxiety levels to rise.

    Will acknowledges that there is a sliding scale depending on how ‘standard’ the build is and how hands-on a self-builder plans to be, but suggests an indicative cost of between £1200 and £1800 per square metre.

    When it comes to build cost, trusting the professionals is important. Will suggests the core three team members would ideally be client, architect and builder, and recommends engaging with the building materials supplier as soon as possible.

    Will says there are ways to prevent the budget being blown by unforeseen problems. If a builder is doing something for the first time, the quote is likely to take into account this increased risk. So it is wise to choose an architect and builder that is experienced with your preferred build system.

    2. Am I getting good value and good quality?

    Will says, “I think this is about being sensible about what your expectations are and also understanding what people’s skillsets are.”

    He argues it is reasonable to want a house to perform in the long term and therefore expect it be built to a high standard. Unlike the volume housing market, self-builders are in more control of this; but success relies on the entire build team sharing a common understanding of what they’re trying to achieve.

    Will recognises that people can be tempted by short-term savings, especially if their project is going over budget. However, these savings will often cost more in the long run; some examples include:

    • A relatively inexpensive paint can peel off or fail in other ways;
    • Plastic baths will always move, leading to gaps along the silicone, and possibly leaks and damage;
    • Internal doors contribute massively to the acoustics of a building and cheap ones won’t insulate noise well.

    Aesthetics can also distract from a product’s core function. Will reminds us that “value and quality are different things to taste.” Concentrate on how something needs to perform, when weighing up options and prices.

    3. Am I paying too much?

    Being new to the build process can mean people worry they are paying too much. Whatever your budget, you will want to feel that you spent your money wisely.

    While a huge budget may make some decisions easier, Will thinks you are better off being wise than being wealthy in terms of the build; of course money is critical, but getting the job done the way you want it is important too.

    A good way to better understand the process, without adding costs, is to network within the self-build and construction environment. Asking how people have used products and materials will help and you can even learn from other people’s mistakes.

    4. How can I find a reliable supplier?

    While big builders’ merchants might compete in terms of service and special deals, they tend to offer a similar selection of products driven by industry standards. Keeping things simple makes life easy for everybody concerned, but this means self-builders typically encounter problems when it comes to getting more in depth advice, especially on less common building techniques. Will explains, “What builders’ merchants are generally not keen to do is to invest an awful lot of knowledge at the counter front or in the branch, because they don’t see a return for it easily.”

    Will argues that there is a need to promote local builders’ merchants, who are more likely to support regional build systems or non-standard construction methodology.

    5. Who do I turn to for help and advice?

    A good starting place is looking at case studies and finding out what other self-builders are doing. For general help and advice, Will says it’s best to talk to someone who has done what you want to do.

    For technical or professional help, he suggests that a sympathetic architect who understands your ambitions can help find tradesmen with the right experience. However, Will also notes that when he has supplied some building companies with new materials, such as lime plaster for the first time, they realised it wasn’t too difficult and were happy to offer this new skill to customers.

    Other avenues of research include the Internet and roadshows. Will points out that this stage of the process doesn’t have to cost much, so it’s well worth testing the water before you spend a lot of money.

    Some of the relevant information might be too technical for the ‘average punter’ and this is where you might have to abdicate responsibility to the experts. For those wanting an eco-home, it can be hard to work out what that might even mean and the right questions to ask.

    Sustainability can mean different things to different people

    An eco-home could be summarised as: benign in construction, use and potentially in disposal. As Will says, “It benefits occupants’ health and wellbeing, it doesn’t pollute the environment and demands very low levels of energy.” He adds that most buildings built using eco principles feel like really nice houses!

    Some people worry that they aren’t creating the best possible eco-home, but self-builders need to set their own realistic goals. Will compares the desire for an eco-home to healthy eating. “Doing something is better than doing nothing. One salad a week is better than no salads a week. And we’re not expecting everybody to be vegan. There is a happy medium that is entirely personal to every single person.”

     

    Find out more

    Visit the website of Ecomerchant

    Follow Ecomerchant on Twitter

     

    Transcript

    Download a transcript of the interview with Will Kirkman
     

    The Future of Housing

    During our interview with Will he mentioned our documentary The Future of Housing.

    This explored the quality of housing in the UK and how we might improve the situation.

    There’s also a chance to see some exemplar projects.

     

    Please connect with me

  • HPH172 : The impact of setting your energy target – with John Palmer from Enhabit

    HPH172 : The impact of setting your energy target – with John Palmer from Enhabit

    John Palmer from Enhabit explains what happens if you choose not to go all the way to Passivhaus standard, including how this impacts on cost, energy efficiency and comfort. He also outlines a best practice approach if you are going to build with Passivhaus principles.

    Interview with John Palmer

    John is the Managing Director of Enhabit, a company that helps to improve building performance, efficiency and comfort levels. John is a qualified Passivhaus consultant, SAP and BRE Assessor, systems engineer and experienced project manager. Prior to joining Enhabit, he ran his own low energy design consultancy.

    First understand the implications of Passivhaus for your project

    If you are trying to set an energy target, John’s advice is to start by reviewing your plans in line with Passivhaus standards. This will allow you to fully appreciate what it might take to achieve Passivhaus. Once the implications are understood, you may take the necessary steps or make a conscious decision to compromise and aim slightly lower.

    Invest in professional advice at the design stage

    John says that Passivhaus is not so much more complicated than a normal build, it just requires more thought at the beginning. One of the key thermal bridges to eliminate or mitigate is where the ground floor meets external walls, which will require careful detailing and potentially some specialist materials. Paying for some extra time with your architect or Passivhaus consultant is a worthwhile investment.

    When clients commission a design review with Enhabit, they are shown a Passivhaus model of their design and given graduated options to see what’s possible with their house and how close they can get to Passivhaus, with indicative costs for extra requirements.

    Focus on a fabric first approach, not eco technology

    John says it’s easy to get bamboozled by all the technology available. Ground source heat pumps, solar panels, boilers, etc. all have a design life of around 20-25 years and will need to be replaced. However the walls of your building will be there for 80-100 years, so the extra investment you put into them at the start will repay itself time and time again.

    Architectural aspirations may make Passivhaus harder to achieve

    John explains that in Passivhaus terms, the shape of your house is the ratio of your liveable area to outside heat loss area. So you may need to compromise on an ambitious design if you want to target Passivhaus.

    If your plans have already incorporated professional advice, and you intend to follow a very high-performing fabric first approach, it may be you just need to add in a MVHR (mechanical ventilation with heat recovery) system.

    Alternatively you may find you haven’t gone far enough with the fabric of the building and need to change the specification of insulation, glazing, etc. This is typical of retrofits, where John says it’s quite hard to achieve the levels required for Passivhaus with the existing fabric.

    Heating a Passivhaus costs a very small amount

    The annual space heating demand in a Passivhaus should be no more than 15 kilowatt hours per metre squared per year. John comments that this is a very specific number and you may decide this is unachievable.

    The key is to understand what number you can get down to, and what that means. For example, a target of 30 kWh will cost you twice as much to heat your property in any given year than it would have done if it were a Passivhaus. But heating a Passivhaus costs very little, so doubling very little isn’t that much and is likely to be better than other new build properties in the UK.

    Every design decision will impact on comfort levels

    Doubling your space heating demand to 30 kWh will impact on comfort but the nature of this impact will depend on why you haven’t achieved the Passivhaus target of 15 kWh. John gives a few examples:

    IssueImplicationsImpact On Comfort
    Insufficient insulation in wallsHeat loss from wallsFeeling cold off the walls
    Poor detailing where walls meet ground floorThermal bridgingIf bad, noticeable cold spots and possible condensation/mould
    Window specification isn’t triple/ high-quality double glazingCold will radiate off the glazingFeeling cold in rooms at certain times of year

    Thermal comfort is all about constant temperatures

    Many homes, especially Victorian buildings, tend to have rooms that are hot near the ceilings but cold at lower levels due to drafts and a lack of insulation below the ground floor. John explains that although the average air temperature in the room might be ok, having cold feet and a hot head will feel uncomfortable! Paying attention to thermal bridges and insulation will help to achieve what John calls good temperature stratification.

    Building regulations rely on people opening windows for required ventilation

    Although our awareness of temperature is quite good, it’s harder to detect poor air quality. We may notice smells and detect when rooms are a bit stuffy, but that’s about it.

    Humidity, VOCs (volatile organic compounds), odours and nitrogen oxide levels are all examples of pollutants within buildings. John advises we need about 30 cubic metres of fresh air per person per hour moving through a property to deal with pollutants, but this isn’t achievable with trickle vents and extractor fans unless you start opening windows.

    An MVHR system will deliver the required level of ventilation, but there are other mechanisms out there superior to extractor fans that will give extra ventilation but perhaps not cost as much.

    Insulation, glazing and ventilation will cost more, but not much more

    These three aspects are typically more expensive than a normal new build, as a Passivhaus requires:

    • More insulation – but you’ll only be paying more for materials (approx. 0.5% increase on overall cost); the labour costs are the same
    • Triple glazing, for thermal performance and to avoid condensation and mould – the gap is closing between triple and double glazing prices
    • An MVHR system – for an average sized house this may cost £9-10k for supply and installation

    Of these, the greatest return on investment will be insulation.

    Some builders are willing to learn

    Hiring the right people to build a Passivhaus is another factor to consider. Although it’s still relatively new to the UK, John has found that builders relish the challenge of doing something that requires more detail and thought; they appreciate the ability to measure how well they’ve done, and revel in achieving the standard. He adds, “You have big, hairy builders hugging each other on site when they get their final air test and they’ve got down to the right levels.”

    Five helpful tips from John

    1) Visit a Passivhaus or speak to someone who lives in one, to see what it can deliver from a living experience

    2) Find out what would be involved in achieving Passivhaus for your project

    3) Understand how each decision affects the final design, floor space, efficiency and comfort

    4) Put an MVHR system in, regardless of your airtightness target; ventilation and air quality are worth doing as standalone

    5) Have some form of quality control in place, even if you’re not targeting Passivhaus, to get the results you’re expecting

    Find out more

    Passivhaus Trust

     

    Transcript

    Download a transcript of the interview with John Palmer

    Please connect with us

    Subscribe, rate and review us on Apple Podcasts

    Like our Facebook page

    Follow Ben Adam-Smith on Bluesky

  • HPH154 : The challenges of building a new home in a rural community – with Jeremy Harris

    HPH154 : The challenges of building a new home in a rural community – with Jeremy Harris

    Jeremy Harris, a scientist by background, wanted a low energy house for his retirement. He talks about the initial stages of his self-build project: finding a plot of land and obtaining planning approval.

    Jeremy Harris

    Interview with Jeremy Harris

    Jeremy Harris, a scientist by background, wanted a low energy house for his retirement. He first came up with the idea that he might like to build a house around ten years ago.

    It’s important to fully understand the beginning of the self-build process

    Jeremy found television programmes and magazines rarely touch on finding a plot, designing a house to fit that plot, and the people you have to employ to do all of that work. It can be very expensive, costing thousands of pounds for planning consultants, architects, building control, etc.

    Plots can seem very nice on websites but look nothing like the photographs in reality

    Finding a plot of land was extremely hard. The Harrises drove several thousand miles, visiting disappointing plots. They began by looking at what they wanted to build, but Jeremy concluded this was the wrong way round: first find a plot, then determine what type of house will fit on it.

    Having walked away from one likely prospect, by chance they found their plot of land 16 miles from where they were living. It was too overgrown to see properly and fenced so they couldn’t get into it, but looked like it might be exactly what they wanted: facing south (i.e. good solar access) and in a sheltered valley.

    There's a plot in there somewhere!
    There’s a plot in there somewhere!

    Buying a plot is not the same as buying a house – ensure services will be available

    When buying a plot of land a solicitor can tell you if there’s a public footpath on it but won’t find out if you’ve got water, mains electricity, mains sewage or even if the boundaries are in the right place.

    Services in rural areas are often stretched to the limit. Jeremy had to ask the relevant utility companies if they could supply:

    1. Electricity? Fortunately there was plenty of power on their doorstep.
    2. Water? Companies have a statutory duty to supply water but the issue is cost. They’d have to dig up a lane for 140 metres and although Jeremy shopped around (anybody with a licence can do the digging), the minimum cost was still £24,500.
    3. Mains sewerage? There’s no statutory requirement to supply this and the cheapest the water company could provide it was £14,800.
    4. A new phone connection? Telecoms companies see self-builders as developers. If there isn’t enough capacity, they can charge whatever they want to lay a new multi-cable.

    As services would cost so much, Jeremy renegotiated the price accepted. The land hadn’t sold for eight years so he persuaded the vendor to knock off a substantial amount.

    Many building plots have boundaries in the wrong place where the Land Registry is concerned

    Plots of land don’t have registered boundaries as a rule. There was a boundary error affecting the Harrises’ plot meaning the house approved to go on it wouldn’t fit.

    The process for resolving boundary errors is complex and time consuming. It’s up to the vendor to do it, so you have to persuade them to spend money with Land Registry to get title plans amended. This often affects adjacent houses, as well as your plot, involving lenders as they have a right on the title.

    A stumbling block can sometimes turn out to be an opportunity

    It took them a year to get their boundary error resolved, but this allowed time to plan the project properly.

    Jeremy wrote a brief with eight key design points but the architects he approached didn’t seem to understand the role of design with low energy houses. Looking further afield for a Passivhaus specialist was an option, but thinking the distance might make communication difficult Jeremy decided he’d design their house himself.

    So the year was productively spent:

    • Evolving designs for the house
    • Tracking down the local Openreach engineer who offered help at no cost, as Jeremy planned to dig trenches on the plot and an underground network would solve local problems with overhead cables and trees
    • Discovering a borehole was possible, at half the cost of mains water
    • Planning a sewage treatment plant, costing around £3,500; much cheaper than digging up the lane

    This avoided inflaming an existing situation with the neighbours, as the plot had a chequered planning history, and saved money too!

    The borehole
    The borehole

    Once the principle of development is established by an approval, it’s extremely difficult for planners to remove it

    The Harrises’ plot had planning permission for a little stone bungalow that they didn’t want. As the local authority had approved the principle of putting a house on the plot, their plan was to submit a new application.

    Areas of outstanding natural beauty, conservation areas and proximity to listed buildings put constraints on what you can build. For example, needing to have all the external materials approved, as was the case with Jeremy’s house.

    Good communication paves the way for a smoother planning application process

    In Jeremy’s area, seven objection letters result in the application being referred to a planning committee, where emotions come into play far more than planning law.

    A previous application for the plot resulted in 14 objections at Parish Council level and dozens of letters. To mitigate objections for their application, Jeremy spoke to every neighbour, sent them regular update newsletters and even Christmas cards.

    He also made scale models, enabling all interested parties to understand the design before the planning application went in. His wife could look inside the rooms to see whether they were big enough, and the neighbours could see what the house might look like in the landscape. And the scale model played an important part at the Parish Council planning meeting, where applicants aren’t allowed to talk.

    model-sw-view-small

    “We had several cases where objectors turned to supporters”

    Jeremy eliminated concerns by talking them through with neighbours:

    Genuine concernsWhat Jeremy did
    New house would overload the sewage systemExplained they were putting in a sewage treatment plant instead
    Height of the house might block views or cast shadowsUsed the 3D scale model to show that the house would be set into the hillside (3m down)
    Being overlooked in their back gardenUsed the model to show that the garage blocked the view (neighbour was also happy the garage protected their vegetable patch from the wind)

    Engaging with local people is important but Jeremy adds a caveat: be cautious and put your foot down if neighbours ask for too much; at the end of the day it’s your plot and your house.

    The Harrises got through the planning stage with no letters of objection at all, so the decision was down to a Planning Officer purely based on the law and planning policies for the area, and approval was granted.

    Transcript

    Download a transcript of the interview with Jeremy Harris

    Find out more

    Check out Jeremy’s blog on the project

     

    Please connect with me

     

  • How to Calculate The Delivered Space Heating Energy in Your Home in kWh/sq.m/year

    How to Calculate The Delivered Space Heating Energy in Your Home in kWh/sq.m/year

     

    A few times in our podcast series we have talked about the maximum space heating demand for Passivhaus (15 kWh/sq.m/year) and EnerPHit standards (25 kWh/sq.m/year). If like me these numbers are starting to stick, then you’re probably wondering how they relate to your current property. Alex Rice has helped me understand all the information you need to do your own calculation. In essence, you need to divide up a year’s worth of space heating energy use by the measured floor area of your house. This is assuming you want to follow the Passivhaus conventions.

     

    The Difference Between Delivered Energy and Primary Energy

    First, you need to be clear about the difference between delivered energy (useful if you’re only interested in how well insulated the building is) and primary energy (which also takes into account how efficiently the heat is generated and is relevant to climate change). Passivhaus uses delivered energy for space heating (15 kWh/sq.m/year) and also has a limit on how much primary energy can be used in total to heat and service the building (120 kWh/sq.m/year). This means if you want your number to be comparable with the PH convention you would need to divide your gas consumption in kWh by the efficiency of your boiler (about 0.6 for non-condensing and 0.9 for condensing) to find out how much heat it has actually delivered to the building.

     

    It’s Time to Measure The Floor Area

    • Exclude the area of stairwells, internal walls, cupboards, plant rooms, doorways.
    • Exclude areas where the room height is less than 1m
    • Multiply areas where the room height is between 1m and 2m by 0.5

     

    Specific Primary Energy Demand (PH = 120 kWh/sq.m/year)

    The first step is to make good use of whatever meters your building has. There’s a very good website called iMeasure which allows you to input your meter readings at irregular intervals and it will attempt to estimate your annual energy consumption. It also takes the floor area and outputs the data as primary energy consumption in kWh/sq.m/year. If you add the two numbers for electricity and gas together you can compare that to the 120 kWh/sq.m/year part of the Passivhaus standard. The normal range is between 300 – 800 kWh/sq.m/year.

     

    Specific Heating Demand (PH = 15 kWh/sq.m/year)

    Finding heating energy is a bit more involved, because most people don’t meter their space heating separately from other end uses, and because people fairly often use wood or oil for heat which can be estimated, but lends a degree of uncertainty. Assuming you heat with gas:

    • Take the gas portion of your consumption and multiply it by the efficiency of your boiler to get the delivered energy (this will be less than the primary energy consumed because some of it is lost as hot exhaust gasses)
    • Next, work out what proportion of that is space heating by subtracting hot water, cooking etc. that is also supplied by the same meter that supplies your heating energy:

    As a general rule of thumb, if you have gas heating and hot water then hot water accounts for about 10% of consumption. More accurately it’s about 600 kWh/year plus 400kWh/year/person, where children are counted as about half a person.

    According to DECC one should allow about 3% of total energy consumption for cooking.

    If you also have a stove you’ll need to make an estimate of how much energy came from wood/coal and add that to the space heating.

    At the end of all that you should know your delivered space heating energy in kWh/sq.m/year which you can compare with the Passivhaus 15 kWh/sq.m/year figure, bearing in mind that Passivhaus assumes you heat to 20ºC all the time.

    Answers for ‘normal’ buildings should be in the range 100 – 300 kWh/sq.m/year.

     

    How do your figures stack up when compared to the Passivhaus standard? We’d love to know. Leave us a comment below.

  • HPH008 : Retrofitting a Victorian House to Passivhaus Standard #1 – with Tom Pakenham from Green Tomato Energy

    Tom Pakenham from Green Tomato Energy describes the practical challenges of making a Victorian house energy efficient. Plus how passive house principles helped a Norwegian explorer in the 1890s.

    Tom Pakenham

     

    Interview with Tom Pakenham

    Tom explains that he wanted to do something about the way we treat the planet and he believed that the best way to do that was by setting up businesses in the environmental sector. It started with Green Tomato Cars, a minicab company which runs on low emission principles. Then the Green Tomato Kit was launched, a green starter kit for the home. The third business in the group is Green Tomato Energy which exists to help people reduce their environmental impact through their homes. They also offer a consultancy service for low energy building.

     

    New Build Not an Option in London

    Tom lives in West London where there are virtually no opportunities for new build and, as he had no intention of moving away from family and friends in the area, it was logical to renovate a property. Most of the building stock is from the late 19th century and early 20th century, and Tom wanted to create a low energy home that was also sympathetic to the cultural heritage and was a beautiful building. A lot of people tend to think of eco homes as looking like bomb shelters or nuclear bunkers. This project set out to dispel that myth.

     

    The Passivhaus Standard is Flexible in Terms of its Application

    Over a year and a half Tom was introduced to Passivhaus. The better acquainted he became with the options, the more attractive the Passivhaus standard became. He particularly liked the fact that it was not a prescriptive way of building and that the principles could be applied to the geometry of the existing structure in order to work out a way of making it perform to the low energy standard.

     

    Attention to Detail is Important

    After selecting your architect and energy engineer, Tom advises to spend time with your design team to make sure what they’re designing will work within your budget and within how you want to live in the property. Don’t rush this planning stage because this is where a lot of time can be saved further down the line. When assembling your team, look for a builder who is not only technically competent but understands what is trying to be achieved and why. This must also filter down to all other workers. If you fail on the detail, then the whole project can come into jeopardy.

     

    Be Prepared to Learn Along The Way

    No matter how much planning is done upfront, when a period property is stripped back there may be some surprises. Tom thinks that as long as you approach the project with an open mind and the understanding that something might change and you might need to learn things as you go along, then you’ll be fine.

     

    The Risk of the Project is More Psychological Than Real

    When Ben expresses a concern about the potential for ruining an old building by carrying out this type of extensive work, Tom reminds him that there is a risk but this is not like jumping down a well! If the project has been designed well and the work has been carried out properly, then it’s not an issue. Its structural behaviour and its energy behaviour is something that can be worked out and designed. Changing insulation or cutting off thermal bridges will have an impact on the joists or brickwork, etcetera, but it can be predicted.

     

    Triple Glazed Sash Windows

    Tom explains some of the challenges around finding windows. In the end he had to have his windows specially made. The top frame is fixed and the bottom pane opens on a tilt or turn mechanism, so you can open it like a door or tilt it inwards. So they’re not actually sash windows. Triple glazed sliding sashes look unlikely to be become popular due to their cost. The issues include the increased weights necessary to balance the extra weight and also how you create a proper airtight seal.

    The big advantage of triple glazing in the city is it acts as a great sound insulator.

     

    Payback in 35 Years

    Although this project was one of the first of its kind, there would still be a straight-line payback in 35 years.  That assumes no capital uplift in the cost of the house. Also as energy prices rise that payback gets shorter and shorter.

    However, Tom doesn’t believe it is helpful to look at it in these terms. He emphasises the comfort and improved air quality of the building: you are creating a great place to live. He gives another example of when you are installing something like a kitchen, you rarely look at the payback and that you really want the great environment it will give you.

     

    Tom’s Top 3 Tips for Renovating a House with Energy Efficiency in Mind

    1. Spend more time planning than you think you need. The work is much easier with a proper plan.
    2. Make sure you have a good team that understand the objectives and buy into the project.
    3. Have enough money to finish. The last thing you want is to be caught halfway through and unable to finish in a completely gutted house.

     

    Watch a Video About This Project (Lena Gardens)

    Tom Pakenham and his design team explain the work that was carried out to this Victorian terraced property.

     

    Transcript

    Download a transcript of the interview with Tom Pakenham.

     

    Energy Efficiency in the 19th Century

    In the last session Ben Adam-Smith mentioned the eco houses from the Home World exhibition in 1981 and he thought that was incredible. However, after attending a talk by Mischa Hewitt from Earthwise Construction at the Retro Expo, Ben is now aware of an eco ship over a century ago.

    ‘The Fram’ of Fridtjof Nansen was a ship built for polar exploration and had many pioneering designs, including in the cabin:

    • Highly insulated cork and felt
    • A triple glazed skylight
    • An airtight layer of linoleum
    • Good ventilation

    According to the 1897 publication ‘Farthest North’ the ship had a stove in the cabin but it was never lit because the temperature was warm and comfortable already. In fact they even thought of getting the stove removed!

     

    Motivating Email

    Ben reads out an email from a listener, Dr James Shorrock, who is about to renovate his own house. He talks about ‘researching the usual heat pump options’ but after listening to the podcast ‘thinks maximising the building fabric/insulation has got to be the best starting point’. Dr Shorrock has also requested a future episode on SIP panels.

     

    The Construction Industry Podcast

    If you like podcasts and you work in construction, Ben recommends checking out The Construction Industry Podcast with Cesar Abeid. There’s relaxed chat with construction professionals, plus Cesar shares some great marketing strategies for your business.

     

    Ask Your Questions or Share Your Feedback

     

    Please Connect With Me

     

  • When Retrofitting on a Budget, is a Piecemeal Approach to Energy Efficiency Better Than Nothing?

    When Retrofitting on a Budget, is a Piecemeal Approach to Energy Efficiency Better Than Nothing?

    When building new there is a very strong case for why you would want to build to a low energy standard such as Passivhaus. Applying the methodology is relatively simple, it doesn’t cost that much more, the buildings will then be easier to maintain and they’ll be more comfortable. If you’re already doing an extensive retrofit of a building, it also makes very good sense to aim for the Passivhaus or EnerPHit standard. This is because the additional work and the additional cost involved is quite limited. As new build and extensive retrofits of buildings don’t account for a huge amount of the work that’s done on UK housing stock what tends to happen is most people do a little bit of work here and there, and maybe when they can stand the disruption and afford it they will do a bigger piece of work. If you find yourself in this position you may be wondering whether to wait until you can afford a whole-house retrofit or to take a few energy saving measures. The crux of this is that with a piecemeal approach it’s very difficult to achieve Passivhaus performance, even if it is practical to produce very substantial improvements in the energy performance of the building. So where does that leave you? Is the money going to arrive any time soon?!

    Cost is still the greatest challenge we face if we hope to bring our housing stock to a low energy standard. Dr Brenda Boardman in her book ‘Achieving Zero Delivering Future-Friendly Buildings‘ proposes that every building and every house in the UK should reach the Passivhaus standard by 2050. It would be a mighty task. [Dr Boardman will be a guest in a future House Planning Help Podcast episode.] For now at least, unless you personally have the money to carry this out, there are no other funding sources available. In the future this may change for regulatory reasons but if you want to be pragmatic in what kind of interventions are practical and good value now (assuming you have made as many lifestyle energy saving choices as you can) you may find yourself back at the piecemeal approach.

    If you go down this route the most important thing is to make sure each of those pieces of work add up to a cohesive whole over time. Set up a trajectory for your building to get it from where it is now to this enhanced performance. Get professional advice, which may be an approach like this:

        1. Look at your energy bills. How many kwh per m2 per year are you using? The figure might be 300kwh per m2 per year.
        2. How long do you intend to live in the property? Typically that could be another decade or two.
        3. What budget do you have available? Energy prices over that time might go up by a factor of 2 to 4, taking a rough guess based on past historical energy prices. If we know your available income based on your pension, in order to be spending about the same amount of money on energy as you are now when you’re a pensioner you need to achieve a certain energy target. Typically this might end up in the range of 50-80kwh per m2 per year.
        4. With an energy target, an energy strategy can then be worked out which calculates what choices need to be made given the constraints. By doing this work piece by piece over a long period of time, you know you will eventually achieve the target.

     

    It’s worth bearing in mind that certain work, such as changing the windows, is quite low impact and can be achieved in a very short space of time. Conversely internal wall insulation will typically make a lot of mess and involve redecorating the room.
    As we start to look at the challenges of retrofitting on the House Planning Help Podcast we will be hearing from Tom Pakenham from Green Tomato Energy about how he retrofitted his Victorian home to the Passivhaus standard. He will also share his advice on how to improve the energy performance of your home.

     

  • When is The Best Time to Improve a House’s Energy Efficiency?

    When is The Best Time to Improve a House’s Energy Efficiency?

    Improving a home’s energy efficiency is a common sense undertaking, but it’s worth considering when you actually do it. The first thing to bear in mind is that the existing building stock is not static, it’s in a life cycle. Eventually all houses will need some maintenance, whether it’s new windows or getting the roof fixed etc. We have to realise that this is the very moment to improve insulation and so on, otherwise it’s too expensive. If the scaffolding is going up anyway then take advantage.

    Also, when you upgrade a component you should go for the best available because it could be 30, 40 or 50 years before somebody needs to do the job again. The key here is not to do a job just to save the energy, as the cost will be considerably more.