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  • HPH012 : Should You Invest in Renewable Energy? – with Dr Derek Taylor from Altechnica

    HPH012 : Should You Invest in Renewable Energy? – with Dr Derek Taylor from Altechnica

    Dr Derek Taylor from Altechnica weighs up the pros and cons of various renewable energy sources and shares his thoughts on whether you should be generating at home. He also talks about his role in creating one of the UK’s most energy-efficient homes.

     

    Interview with Dr Derek Taylor

    Dr Taylor trained at the Architectural Association but got interested in renewable energy and low energy building design in 1972. From then he started to pursue more of a renewables orientated career and did a masters in designing wind turbines and renewables, and came to the Open University. He is particularly interested in bringing together renewable energy and architecture to try and make it much more effective.

     

    There are still Fossil Fuels Available But CO2 Emissions are the Problem

    A lot of people believe we have reached peak oil and that we are now at the point of depletion. There’s still a lot of coal in the ground and a fair amount of gas available but their CO2 emissions are a big concern for climate change. It’s clear we need to make a step change. The scientists say we need to cut CO2 emissions by 80% in the next few decades.

    Cooling tower

     

    UK’s Best Renewable Energy Source is Wind

    In terms of renewable energy Dr Taylor believes wind energy and offshore wind energy offers the most promise to the UK. He explains that 40% of the potential wind energy resource in Europe is actually in the UK. That figure is looking at land based resources, with even more potential offshore.

     

    Phenomenal Increase in Wind Power

    Dr Taylor has recently been updating the wind energy section of the Open University renewable energy course. He noted that in the year 2000 there was about 30,000 MW of wind energy globally whereas in 2010, there was 38,000 MW installed in just one year. Now globally there is over 200 GW. Dr Taylor is impressed with the progress. The UK currently has the largest offshore wind farm in the world, which is off the coast of Thanet (installed by Swedish company Vattenfall), and they’re currently building a third offshore wind farm in the Thames Estuary, called the London Array, which will produce a fair proportion of London’s electricity needs.

    Wind-farm-on-hill

     

    Floating Wind Energy Technology Has a Huge Potential

    Tapping into floating wind energy technology, the wind energy resources in UK waters would be equivalent to the Gulf Oil reserves but every year.

     

    Renewable Energy Solutions Fit into Different Scales

    Generally there are three types of solution: building scale, an intermediate scale – which Dr Taylor calls neighbourhood or community scale – and large scale.

     

    Solar Makes The Most Sense For Buildings

    In terms of buildings, solar energy often makes the most sense for electricity generation, hot water and also for reducing space heating loads. In the summertime it can be used for cooling.

     

    Heat Pumps

    The temperature of the ground below a certain depth is constant throughout the year, so this provides another ambient source of energy.

     

    Wind Energy Isn’t Normally a Good Solution for Urban Areas

    The usability of renewables depends on the location as to whether they will perform effectively. Wind energy can make sense but in most cases it doesn’t in urban areas. Wind energy technology usually starts to make sense at community scale upwards, for example, a medium scale turbine might be appropriate for a village or a town. Costs can then be spread amongst householders.

     

    Former Watermill Sites Could Have Potential for Hydro Power

    The best sites for hydro tend to be in mountainous areas, but Dr Taylor suggests that former watermill sites could be good places to generate. It’s important to note that when watermills were in use there was less water extraction so there was more water running through the system. Dr Taylor did a renewable energy study for Merton Council which found that a short stretch (19km) of the River Wandle once had about 90 watermills in operation.

    Old Water Mill

     

    Biofuels Make Most Sense When it’s a Waste Product

    Growing energy fuels is very difficult to justify when you haven’t got much land. A forested area can obviously provide wood as a fuel. Dr Taylor believes the situation with biofuels probably makes sense if you can use it as waste, such as food waste and oil waste. You can then process that with biology to produce gases and fuels. In Denmark there are community digesters where manure, food waste and sewage combine to produce methane – the process mimics a cow’s stomach and produces gas that can run small power stations.

     

    Tidal Barrages Expensive to Build and Maintain

    The main problem with tidal energy is that it’s been exploited using tidal barrages, like a big dam across an estuary. These are very expensive to build and can impact on the rich eco systems. In France, there is an example of a successful barrage called La Rance.

     

    Tidal Stream Technology Shows Promise

    Essentially they are underwater wind turbines which capture the currents as they flow around the coasts. One of the big advantages is that because water is 800 times denser than air for a given size of rotor diameter you get a lot more power out compared to wind turbines because air is very low density. This means much smaller devices can give more power output. The downside is that these devices are situated in difficult locations and have to be able to cope with the water reliably. They’re still in the early stages of development.

     

    Devices Built to Harness Wave Energy Have to Survive The Stormiest Seas

    Dr Taylor reckons that wave energy is an even more difficult one to achieve. The energy resources from the waves are substantial but you have to build devices which can survive 24/7 in the most stormy seas.

     

    Failures Important to Progressing the Technologies

    Very few of the wave energy projects actually go through the iterative stages that are needed to develop a technology. Lots of funding goes into building one device and that fails and there’s no money to carry on. Those failures are vital to progressing the technology.

     

    We Can Use Fossil Fuel Reserves Much More Effectively

    While fossil fuels might still be available, Dr Taylor believes that the price will be the main constraint to using them. He stresses how in other countries they’re actually much further on with many aspects of design, performance of houses and also the use of wind energy.

     

    Combined Heat and Power Makes Use of Waste Heat

    One approach for district heating is to use the waste heat from power stations to heat houses. Dr Taylor calculated that if you add up all the energy being lost from the cooling towers around Britain, it amounts to more energy than is used to heat all the houses in Britain. Currently this energy is just allowed to go into the atmosphere or into the sea at coastal locations. In Denmark 65% of houses are heated this way or from large scale boilers. To achieve this heat mains are laid under roads or gardens and each house is then connected up. Part of the difficulty is that electricity networks are privatised and they would rather do what they’ve always done.

     

    Heat Stores Play an Important Part

    Dr Taylor explains that Battersea Power Station was a combined heat and power station when it was operating. There was a pipe under the Thames which provided heat for 4000 houses in Pimlico. They’ve subsequently re-installed a small combined heat and power station at Pimlico which delivers the same thing. Part of that scale of development enables very large heat stores to be built in, so that heat can be stored when you’re generating electricity for use later. Heat from other sources such as solar or wind energy can also be used to charge up the heat stores.

    London Battersea powerstation

     

    Nuclear Energy is Expensive and Funding Must Be Offset to Look After The Waste

    In France about 80% of their electricity comes from nuclear, but this doesn’t mean its future is clear. Not only is it expensive but disposing of nuclear waste is still a big problem. How much money will be needed in the future to look after nuclear waste from the past? There are also discussions about what’s going to be the most useful type of fuel after uranium.

     

    Low Energy Buildings Fall into Two Strands

    Historically there are two strands of developing low energy buildings. One is known as the super insulated approach that tends to be a lightweight construction with lots of insulation. The other approach is known as passive solar, which is reliant on lots of solar orientation, lots of glazing and high thermal mass. The solar gains are trapped in the thermal mass so that it acts like a storage heater.

     

    Super Passive Solar

    In the UK passive solar hasn’t worked well in the spring or autumn times when there tends to be quite high cloud cover. There is also not much benefit in the winter time whereas super insulation then works well. So a super passive solar approach combines the two so you have a high level of thermal mass but it’s inside a super insulated envelope. Dr Taylor worked on a house in Herefordshire which might be one of the UK’s most energy efficient homes.

     

    Super Passive Solar Goes a Step Further Than Passivhaus

    Dr Taylor really likes the Passivhaus standard although he finds it unfortunate that they chose the name Passivhaus as it’s easily confused with passive solar. It is really an ultra super insulation approach. The Passivhaus design system doesn’t really take into account the thermal gains from thermal mass, so you can’t get that extra point further of actually optimising the design to get to zero space heating, although a lot of Passivhaus buildings are getting pretty close to that.

     

    With New Builds, Push the Envelope as far as You Can

    For new buildings Dr Taylor thinks you have to push the building’s envelope as far as you can because it’s much more difficult to upgrade. If you can design as much insulation as possible and get to Passivhaus standards then it will be well worth doing and shouldn’t cost you a great deal more on top of the building.

     

    If You Have The Money, a Passivhaus Retrofit Can be a Good Investment

    Upgrading an existing building to Passivhaus is not a cheap option. However it’s probably better using that money to go into the building’s fabric rather than getting an expensive new kitchen!

     

    Internal Insulation Must be Done Correctly or You Risk Damaging the Building

    External insulation is a much easier solution but risks affecting the aesthetics. The problem with internally insulating walls is that there will be a reduction of floor area. Also, with solid walls, for instance, prior to that wall being internally insulated, it’s been kept warm by the space heating of the house but once the insulation is between it and the heating then it’s obviously a cold object and it’s a cold surface. So, unless the internal insulation is done correctly, if any vapour gets into that structure it will hit the cold wall and condense. This can cause rotting problems.

    craftsman insulating a wall

     

    Combined Heat and Power Could Buy us Some Time to Retrofit

    Dr Taylor refers back to how we might reduce the CO2 emissions from buildings. Investing in combined heat and power, and district heating would enable the existing buildings to start to use heating which is actually low carbon. It would also buy some time to upgrade the performance of the existing housing stock.

     

    We Only Have One Chance to Make our Homes Energy Efficient

    In order to reach 80% reductions in CO2 Dr Taylor believes that we must go beyond a little cavity wall insulation. He thinks we only get one shot at this and it should be done properly. The challenge will be funding it. If there were a scheme where everyone was connected to a heat network then there’s a potential revenue stream for the sale of that heat to people which could be used to fund insulation of buildings down the road.

     

    Incremental Improvements Should Have a Long Term Plan

    Try and have a plan or a strategy so you’re not going to foreclose on the options. Do the thinking upfront so that improvements compliment each other. If you have a loft that can be insulated then certainly the more upgrades you can do to that the better.

     

    Dr Derek Taylor’s company

     

    Transcript

    Download a transcript of the interview with Dr Derek Taylor.

     

    Goals for House Planning Help in 2013

    Ben Adam-Smith outlines his objectives for making House Planning Help an even better resource. This includes:

    • Getting more detail into each podcast episode
    • Creating more videos for the House Planning Help YouTube channel
    • Hand-picking more industry experts as guest bloggers
    • Hosting Google+ Hangouts to debate key issues

     

    Regen Media Wants to Help Your Business

    Regen Media produces the House Planning Help Podcast. Ben Adam-Smith explains how if you are in the UK and you need video or audio for your business, then Regen Media wants to help you. It is very important to have a presence on multiple platforms in the age of the Internet so that your company can be heard above the noise! Regen Media can create media that will do this and market your business in a much more dynamic way than advertising. Contact us today to find out more.

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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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