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Tag: Retrofitting for energy efficiency

  • HPH072 : A Radical Retrofit of an End of Terrace House – with Tim Nicholson

    HPH072 : A Radical Retrofit of an End of Terrace House – with Tim Nicholson

    Tim Nicholson reveals why he chose to retrofit rather than build new and, having selected a suitable property, what the strategy was and why. Tim has also been blogging about the experience on his website Oxford Green House.

    Tim Nicholson

     

    Interview with Tim Nicholson

    After refurbishing his previous home to be more energy-efficient Tim was intrigued to take his new home, an end of terrace property, as far as he could go.

    At the heart of this retrofit was a strategy using high levels of insulation and making the building extremely airtight.

    End of terrace ripe for retrofitBefore the retrofit

    Difficulties in Finding a Building Plot in Oxford Led Tim to Embark on a Refurbishment

    With sites being so difficult to come by in Oxford, due to limited availability and high prices, Tim decided to address some of the problems with the UK’s existing housing stock and take on a radical, energy-efficient retrofit.

    Externally Insulating the House Ensured Internal Floor Space Wasn’t Compromised

    Planning restrictions led to the decision to externally insulate the building and clad it in a new brick skin, in order to maintain the existing aesthetic. They also benefited from the thermal mass, no loss of floor space and a reduced risk of interstitial condensation.

    Proposed external insulation Neighbours objected to this proposed render finish  

    Being a Terraced Property Led to Additional Challenges

    Neighbours were concerned about the ‘step’ that would be created by the additional wall, so permission was only given to clad the rear and gable walls, with internal insulation being required for the front of the house.

     

    Laying Floor Insulation Was Ambitious and Costly

    With the existing flooring being uncomfortably cold, the decision was made to dig out the existing concrete slab and the dirt beneath it, in order to lay 20cm of polystyrene EPS insulation. They found this process to be noisy, expensive, time consuming and generated a huge amount of rubble.

    The floor slab is dug up

     

    A “Skirt” May Have Been a Better Option

    Given the challenges of breaking out the concrete slab, Tim in hindsight concedes that an insulating skirt may have been a good option. This means digging a trench down the external wall to the foundations, and laying insulation in order to insulate the walls below ground and to reduce the heat loss from the building in that area. It would not have been as efficient but would certainly have been cheaper.

     

    Renting the House Next-Door Enabled the Family to Remain on Site Throughout the Project

    It became apparent that living in the house while carrying out the refurbishment was going to have many challenges. Luckily the neighbouring house was available to rent for a time which meant they could always be there to take deliveries and ensure the site was secure.

    Ground-and-first-floor-plans

     

    The Layout of the House has Been Adapted to Suit the Needs of the Family

    While carrying out the retrofit the family also took advantage of the chance to change the layout so that it would better suit their needs. This has resulted in a more open plan area downstairs which is much lighter and uses the new stove to heat the space more efficiently.

     

    A Wood Burning Boiler Stove and Solar Thermal System Provide the Hot Water and Heating

    The property has been disconnected from the main gas supply. The wood burning boiler stove will provide the hot water and heating at times when there isn’t enough being generated by the solar hot water system.

    Solar thermal and solar PV

     

    Refurbishing Rather Than Rebuilding Was a Better Option

    With all the works taking place, and particularly given that it could be argued there wasn’t too much left of the original, knocking down and rebuilding the property could have been considered. However, being end of terrace it would have been extremely challenging with regard to the neighbouring properties.

     

    It Has Been an Expensive but Worthwhile Process

    While the works have been costly, Tim sees it as being a dual process of carrying out a high standard refurbishment and also creating an energy efficient home. Any extra investment in using the high quality products he believes is reasonable when looking at it over their lifetime.

     

    Too Much Hot Water Has Resulted in an Underfloor Heated Log Store!

    On days where there has been a lot of sunlight and not so much consumption, the large solar thermal system has continued to produce hot water to the point where it was boiling in the cylinder. Tim describes how they now divert any excess by pumping it down to their log store to help dry out the logs for winter.

     

    Tim Hopes Their Lessons Learned Will Help Others Carrying Out Similar Projects

    By sharing information on their website about the suppliers they have used, products specified, and their decision making processes, Tim hopes that anyone else doing a similar retrofit can learn from their successes, failures and experiences.

    Find Out More

    Visit Tim’s website Oxford Green House

     

    Transcript

    Download a transcript of the interview with Tim Nicholson.

     

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  • HPH016 : Finding The Balance Between Heritage and Sustainable Design

    What’s more important – preserving heritage architecture or retrofitting it to high energy efficiency? In our first forum on a Google+ Hangout we discuss some of the issues.

     

    The Panel

    Writer and blogger Roger Hunt (who appeared in our 10th podcast)

    Writer and Passivhaus consultant Adam Dadeby from Passivhaus Homes (who appeared in our 5th podcast)

    Homeowner Ross Atkin (who has recently retrofitted his Victorian house)

     

    This debate was primarily focussed on buildings that were constructed before 1910 or the time when building technologies changed.

     

    When Retrofitting, There is No Single Approach That Fits Every Building

    In historic buildings where the façade is a strong part of the character, externally insulating would not be appropriate. However, just as importantly, internally insulating would cause major disruption as well, particularly if many of the original features are intact. So, when retrofitting an old house for energy efficiency, each building must be assessed individually.

    From a purely energy point of view and from a moisture point of view it’s much better to insulate on the outside of a wall and to wrap the existing building in insulation.

     

    Old Houses May Not Need a Deep Retrofit

    If the definition ‘old houses’ is a small enough percentage, for example between 5% and  10% of the total housing stock, then it is possible that these houses could be retrofitted in such a way as to minimise damage to their character. If energy consumption were reduced, perhaps by 50%, while the remaining 90% or 95% of the housing stock is brought up to Passivhaus levels, saving 80% or 90%, then the overall the situation would be much more in line with where it needs to be.

     

    Occupants of Old Houses Must be Willing to Live Like the Inhabitants of the Previous Centuries

    In an energy constrained future, for those who choose to live in an old house, compromises must be made. The inhabitants must consider that they adopt a lifestyle that is more like how things used to be in previous centuries, where they lived at colder temperatures. In winter, the inhabitants might retreat to a smaller portion of the house. Since the 1970s the temperatures of our homes have gone up from 12 degrees to 19-20 degrees (on average).

     

    Old Houses Could be Vulnerable if Not Made Energy Efficient

    There is a danger that as energy prices increase, people are not going to want to buy buildings unless they are energy efficient. As it is easier to construct low energy buildings from scratch than it is to retrofit them, more old houses could fall victim to demolition. Making old properties as energy efficient as they can be without destroying the character will help. The rest is down to accepting this overall colder temperature, which will only be in the winter months anyway.

     

    Simple Measures Can Really Improve Energy Efficiency

    There is a lot that can be done to improve energy efficiency that isn’t going to cause damage and destroy the character and value of the buildings. For example, draught proofing is relatively easy to do and doesn’t have a huge impact on the building. A certain level of insulation can be done without having a huge impact on a building.

    Every house must be individually understood and then appropriate measures should be carried out in a sensitive way.

     

    A Passivhaus Retrofit for Many Old Houses Wouldn’t be Appropriate

    Retrofitting an historic house to Passivhaus standard by insulating internally would effectively involve building a house within a house. That would mean gutting the place. While this could still be appropriate where significant damage has already occurred, for example the Princedale Road Passivhaus in West London, it is unlikely to be a solution to roll out.

     

    The UK is Stifling Advances with Conservation Overkill

    The balance between conservation and actually providing housing that works for people in terms of health, energy costs and the environment is weighted too heavily in favour of conservation in the UK. The planning system often treats everywhere as a conservation area, when this is not the case. All this does is preserve the status quo rather than allow progress.

     

    A Proportion of Society are Stuck in Their Period Properties

    With investment in social housing, the very poor are getting a much better standard of housing. Those that are wealthy can also afford to self-fund energy efficiency measures. However, there’s quite a large percentage of people in between, either unable to fund changes or perhaps stuck in rented accommodation. These people aren’t choosing to stay in heritage accommodation, it’s simply what is available and what they can afford.

     

    There Needs to be More Education

    People still do not seem to have the knowledge of how they can make their homes better and more energy efficient. Even those who live in eco houses quite often do not fully understand how to live in them. There needs to be more help available.

     

    Social Housing is Leading The Way in Eco Retrofits

    It doesn’t seem to be volume house builders that are leading the way, but housing associations. They’re the people that are experimenting, coming up with the ideas and solving the problems. There is a lot to learn from the social housing sector.

     

    Need to Solve Damp Issues

    No house should have damp issues, but they can stem from mistakes that have been made in the past. Before retrofitting a house these issues should be addressed because a damp house is a cold house and a wet wall is a cold wall. Stopping dampness will create a much warmer and more environmentally friendly house in the first place.

     

    In the UK, VAT Encourages New Builds

    Paying 20% VAT on retrofits as opposed to nothing on a new build sends a clear message. As retrofits are more complicated anyway it does favour knocking buildings down and starting over again, especially in areas where skills are limited.

     

    The Focus Should be on Creating Decent Homes

    Lifestyle plays a big part in energy efficiency so it’s not just about buildings. For example, switching on all the lights and leaving the windows open in an energy efficient house will have a negative effect. So while the fabric of the building is important, there is also a fundamental lifestyle change that must be adopted. The future of housing should be creating decent homes for people, considering the environmental aspects, the energy usage but also things should be clean, dry and healthy.

     

    Transcript

    Download a transcript of the debate.

     

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  • HPH009 : Retrofitting a Victorian House to Passivhaus Standard #2 – with Alex Rice from Green Tomato Energy

    Alex Rice, Senior Engineer at Green Tomato Energy, explains that there are few technical challenges that remain when retrofitting a period home into a low energy building and it is a case of how you apply those solutions to the given building.

     

    Interview with Alex Rice

    Alex talks about the process of how his clients (often a husband and wife team) get started. He stresses the importance of trying to understand their needs and ideas, as well as discussing what is possible. This enables a clear brief to be written with objectives about which everyone is clear.

     

    Create and Stick to an Energy Target

    In many of projects undertaken by Green Tomato Energy they set targets to reach the Passivhaus (15kWh per m2 per year) or EnerPHit (25kWh per m2 per year) standards. Where listed buildings are concerned the target might be slightly higher due to the constraints. However, it is really important to nail down an energy target, because without knowing what you are trying to achieve in terms of energy it is nearly impossible to make the technical trade-offs that are required. This target guides the decisions that are subsequently made, thus changing your target practically changes the entire design.

     

    Understand the Building Itself

    Each building is unique and so understanding how it was originally intended to work is imperative. Alex highlights how Victorian dwellings function in a very different way from modern buildings in terms of how moisture moves around the building and the way they’re ventilated. Even the way people lived in them was different. In order to take that building as it was designed and make it work in a way that is almost completely different, you’ve got to have a really good understanding of the materials and the methods of construction that were used.

     

    Moisture is Death to a Building!

    Ben confesses he doesn’t really understand about moisture but he knows you don’t want to trap it. Alex explains that nothing kills a building more quickly than it being wet. He illustrates the point by saying a derelict building will stand for ages until the roof falls in and then it will disintegrate very quickly. Moisture causes wood to rot and bricks to undergo freeze-thaw damage. The primary aim of a building is to keep the building materials dry. Controlling sources of moisture from within and outside the building is crucial to the long term survival of any building.

     

    Where is The Moisture Coming From?!

    People are a source of moisture inside the building! They do things like wash and cook. They dry their clothes on radiators and water potted plants, etcetera. Then the other source is water outside the building including rain falling on the walls, water soaking up through the foundations, leaking out of gutters and coming in through faulty roofs.

     

    When Setting an Energy Target, Why Don’t We Always Go For The Best?

    The best target depends on the building and what you’re trying to achieve. For zero energy consumption, your house would be infinitely big which is clearly not possible. Trade-offs have got to be made between how thick your insulation is and what energy sources are available to provide heat. For example, if you have a Passivhaus that has very poor orientation so that you can’t get some south facing windows, then your insulation is going to need to be thicker in order to make up for that. There’s a trade-off between how much energy the building consumes, how expensive it is to build it, how much space it takes up and how costly it is to service the building, so the concept of Passivhaus is that you make the building envelope perform well enough that you can dispense with some of the techie bits of the building – parts of the heating system.

     

    The Passivhaus and EnerPHit standard are carefully selected

    The whole point of 15kWh per m2 per year is that it’s a point of minimum cost for that level of performance. The same principle applies to the EnerPHit standard, because in a retrofit project, getting the insulation in and getting the thermal bridges insulated is more expensive so it becomes cost effective to spend a little bit more on the energy and a little bit less on the building.  Those two points 15kWh per m2 per year and 25kWh per m2 per year were picked carefully as the best level of energy performance but built into those two numbers are assumptions about how much it costs and how difficult it is to achieve those standards, which is why when you go to things like listed buildings that number moves up, because it becomes cost effective and practically achievable to consume a bit more energy a year but make it much easier to build.

     

    Internal Wall Insulation vs Reduction of Floor Area

    It is Alex’s experience that you can put a surprising amount of insulation on the inside of a room and that once it’s all detailed in, you hardly notice it. When you’re putting it on it looks huge, but once it’s detailed in with the plasterwork, it really does disappear. The only exception is where space is already limited and therefore things like beds and wardrobes no longer fit into spaces that they previously did. There are higher cost ways of achieving the same level of insulation performance in less thickness using aerogel, vacuum insulated panels, etcetera. Generally speaking phenolic foam and those types of insulation materials are perfectly adequate and are the most cost effective choice for retrofit projects.

     

    Add Space as Part of The Project

    If you are retrofitting to Passivhaus or EnerPHit, then this is a major undertaking and thus this is the perfect time to extend your property. At this Lena Gardens Victorian terrace, a basement was dug out to provide space for the services and an extension at the rear enlarged the kitchen. So in this case there was more floor area at the end of the project.

     

    The Geometry of Old Buildings Make Insulating More Challenging

    One of the biggest challenges in a retrofit is working around the existing structure of the building. In a new build the walls can be made with the insulation in it already and it’s quite easy to design a thermally bridge free well insulated envelope. In an existing building there are often areas which are geometrically difficult to insulate.

     

    Removing The Timber Bricks!

    A lot of old buildings contain some timber in the walls. It was typical in Victorian construction that if something was brick-sized and brick-shaped then it would be stuck in the wall! This can only be assessed once the plaster is removed. It’s important to make sure the pieces of the building you are covering up are in a fit state to remain covered up behind insulation for the next few decades.

     

    Avoid an Adversarial Culture in Your Team

    Alex emphasises that communication amongst the team is key to the success of the project. The guys on site need to report issues as they arise and not feel that they will get an earful of criticism in return. As Alex can perform many of the tasks himself, he sees this as crucial in building up credibility with the tradespeople.

     

    Tradespeople Want to Work on a Passivhaus Project

    One of the indicators that a tradesperson is going to be good on this type of project is that they have previous experience. Tradespeople are becoming aware of this and they want to do a Passivhaus project because they realise it will be good for them to be known to deliver this level of quality. Passivhaus is becoming a hallmark of quality. Alex describes how after seeing a blower door test for air tightness for the first time, tradespeople often leave the site excited about the new knowledge they have learned.

     

    Alex Inspired By Ken Schaal From CommonWealth Solar in Virginia

    After studying for a degree in new and renewable technology at Durham University, Alex worked at CommonWealth Solar in the United States for Ken Schaal. Ken was part of the passive solar homes movement of the 1970s and had built a geodesic dome (using materials such as foam and concrete) for next to no money that also used practically no energy. Having lived in Victorian properties all his life, Alex describes this as an eye-opener as he always expected low energy buildings to be complex and expensive. Ken taught him that if you make a building well-insulated and airtight, you need the minimum of stuff to make it work.

     

    British Housing Stock is Very Different to America

    In the United States, buildings are often knocked down every 25-50 years to make way for the new designs. In the UK, the average life of a building is often a hundred years or more. Thus retrofitting is a major challenge for the future.

     

    Transcript

    Download a transcript of the interview with Alex Rice.

     

    UK Passivhaus Conference

    Having become more and more interested in a Passivhaus approach over the last few months, Ben Adam-Smith attended the UK Passivhaus Conference in Nottingham. There were some very interesting talks and Ben reveals that he has been taking notes on who he needs to speak to for future episodes!

     

    Is Cladding with Brick Pointless?

    Ben is confused about the options for his own project as he prefers more traditional aesthetics, yet he can completely understand why many Passivhaus buildings are finished with wood (which is far more sustainable) as the external surface. He wonders whether he just has to get used to it, as using an unnecessary layer of bricks on the exterior of a house is a waste of time and resources (even though he still likes the effect).

     

    Voicemail Message from Shauna Wyldeck-Estrada

    Shauna contacts House Planning Help to share information about her renovation of a Victorian house in Catford South. She talks about how she used sheep’s wool insulation in the loft and cellar, and how it has had an amazing effect on reducing her bills. A wood stove provides heat when required, making her central heating system redundant.

     

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