Green, green grass of home: Norwegian turf roofs

For a moment, let’s leave aside the technical benefits (or otherwise) of green roofs, and just enjoy how they look in the landscape.

In an article for the forthcoming ESI.info Expert Guide on facades, roof finishes and rainwater management, director of the Future Cities project Austin Williams writes:

Green roofs are now lauded for their biodiversity, carbon neutrality, pollution-busting, happiness-inducing, rainfall attenuating, energy-saving goodness. Putting grass on a roof has evolved into a moral agenda that almost brooks no challenge … Specifiers need to be aware that green roofs are not a miracle cure.

This turf roof blends almost seamlessly into its hillside surroundings. Spot the chimney and small skylight on the left!

Needless to say, green roofs alone won’t meet all the challenges involved in creating a built environment that really works… Sometimes it’s good to view them from a purely aesthetic angle.

That is just what I did last August in Norway. On many of our walks during those two weeks, there were turf-roofed cabins round every corner – although because of their camouflage tops, we often did not spot them until we were right up close.

Most of the pictures in this blog post were taken at or around Herdalssetra, an isolated hill-farm that has been in continuous operation for over 300 years. The 30-odd buildings here are generally small, old timber shacks. Their turf roofs are simply a part of that vernacular and a reflection of which materials were most readily to hand at the time. However, we often saw green roofs in new-build housing developments in major cities like Oslo and Trondheim.

This post, then, is intended as a low-tech visual feast and nothing more. I hope it conveys some of the beauty of the Herdalen valley. Look at these pictures and imagine the bleating of goats, the crunching sound of fjord horses grazing in juicy pastures, the smell of sun-warmed juniper and dwarf birch, all to a backdrop rush of snow-melt waterfalls – and you’re half-way there!

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Set in stone: time travel at BGS Keyworth

The recently opened Geological Walk at British Geological Survey’s headquarters in Keyworth near Nottingham crams three billion years of the Earth’s history into a beautiful, 130m long stone concourse. Stephen Parry (Mineralogist and Petrologist at the BGS) and Michael Heap (Managing Director of expert natural stone suppliers CED Ltd) did the time-walk with me.

An ammonite-bearing block of Portland limestone

Each step on the Geological Walk takes you 25 million years closer to the present day. What can we learn from this ambitious project?

A burning issue: should we really be subsidising the biomass industry?

Is the extensive burning of biomass for electricity generation a good use of (arguably) renewable resources and an important contribution to the low-carbon economy? Or is it in fact a threat to our environment and the timber industry, and an inefficient use of a very valuable resource?

In this guest post, Stirling-based building product manufacturer Norbord argues the latter.

What is the most responsible use of timber?

The background
Wood is a valuable resource, which, unlike other sources of renewable energy, is limited due to available land area and the length of the growing cycle. In the UK, current sustainable harvest is fully utilised by Norbord and other manufacturers through a lifecycle of grow –> use –> re-use –> recycle – and then, and only then, –> recover for energy.

This responsible and environmentally efficient lifecycle ensures carbon is stored for many years before being released back into the atmosphere when it is finally burned to produce energy.

As part of its commitment to a low carbon economy, the Government has introduced subsidies to electricity generators under the Renewables Obligation (RO). These subsidies incentivise the burning of wood for electricity-only generation, at efficiency levels of less than 30%.

The issue
The wood panel industry relies entirely on UK wood (virgin and recovered), which is now under huge pressure from the large-scale biomass energy sector. In simple terms, our industry is under threat because the Government subsidies allow the energy generators to pay more than double the price currently paid by the UK wood panel industry for its primary raw material. As a result, this has driven up average wood prices by 60% in the last five years.

And the problem looks set to grow. There has been a huge increase in the number of planning applications for biomass power stations that generate electricity by burning wood. These plants have the capacity to consume many times the entire UK’s timber harvest. Additionally, the Government is introducing subsidies with respect to the Renewable Heat Incentive (RHI) scheme, which will further distort the market.

Biomass protest (image by faul on Flickr)

The impact
The threat to the wood panel industry is clear, however the current legislation has wider-reaching consequences too:

• The loss of the wood panel industry would cost tens of thousands of jobs across the UK, many of them in manufacturing, damaging already fragile economies.
• The environmental impact – the inefficient burning of wood will in fact generate a net increase in UK CO2 emissions, to the order of hundreds of millions of tonnes.
• UK bill-payers, already struggling with rising costs for household energy, are actually paying £810 million a year for these so-called ‘green’ subsidies through hidden charges in their bills.
• Consumers will experience significant price increases on wood panel products and other manufactured items, driven by the rising cost of raw materials.
• Large negative impact on the UK’s balance of trade, as we would need to import wood from overseas to meet demand.
• Distortion of the ‘Hierarchy of Use’ for wood, to which the UK Government is committed.

What’s being done?
The Wood Panel Industries Federation’s Make Wood Work and Stop Burning our Trees campaigns are backed by Norbord and the other UK panel producers, and supported by other forest product industry organisations. They are national campaigns aimed at persuading the Government to encourage the best possible use of this valuable and limited material.

Working with leading organisations within the building trade, we are lobbying the government to review current and proposed legislation. An Early Day Motion has been tabled in Parliament in support of the Make Wood Work campaign. Specifically, we are asking the Government:

1. To respect the obligated “Hierarchy of Use” in the framing of legislation.
2. To review the RO and RHI incentives with respect to their distortion of this Hierarchy.
3. To incentivise the use of wood for energy only after its full lifecycle use, for carbon storage.
4. To better integrate the process across disparate Government Departments.
5. To commit to, and deliver on, an expansion of productive woodlands.
6. To engage fully with the wood processing industry as represented by the Wood Panel Industries Federation (WPIF) and Confor (Confederation of Forest Industries).

How can you help?
The Biomass Issue has consequences for the UK economy, our environment and for the tens of thousands of UK workers whose jobs are at risk as a result of this legislation.

Please support our campaign by signing the petition.

—

Thank you to Norbord for this guest post. What are your views on biomass and the Government incentives? Whether you are in opposition to the above or in support of it, I would love to hear from you.

In the meantime, here is some more background information:

• A post on a new biomass-fuelled power station from our ESI.info Environmental Engineering blog last year, which sparked some debate
• An Urban Times article on a Princeton student exploring the use of bamboo as a biofuel

The great PV break-through

Ross McGuinness is Area Sales Manager for Kingspan Insulate and Generate. In this guest post, he celebrates the unprecedented take-up of solar PV, but warns it’s too early to break out the Champagne just yet…

The massive expansion of solar PV capacity in the UK has passed another milestone recently. Just a couple of weeks ago, SPV broke through the symbolic barrier of 1,000MW of installed capacity.

Sunset reflected in a solar panel, by ToGa Wanderings on Flickr

This growth has been rapid: in April 2010 there was a mere 26MW installed nationally. 23 months down the line and the industry has topped 1GW, which is a stunning result. The driver behind this seismic shift towards green, renewable energy is without a doubt the government-backed Feed-in Tariff (FiT).

This is all very positive news, and with the announcement from the Department of Energy and Climate Change some weeks ago stating their wish to have 22GW installed by 2020, you could be forgiven for thinking that everything is rosy in the SPV garden.

This announcement of several weeks ago has set out something of a roadmap for PV, but key questions need to be addressed before the industry will come out and support the new policy.

The government has destroyed any trust it may have had with the sector and it will take quite some time to repair what has become a fractious relationship. Continued court actions and appeals mean that, in the short term at least, a cloud hangs over SPV in the UK right now.

Looking at what is proposed by government, many industry insiders believe that it will be challenging to convince consumers to invest in SPV at the new rates. One of the main drivers of SPV has been the willingness of investment firms to “fund” SPV, hence the plethora of “free” installs whereby the end user got the benefit of free or discounted electricity and the funder got the Feed-in Tariff.

The new FiT rates will make it unlikely that similar funding models would be viable from an investor perspective. Funders look for an IRR of a minimum return of 7%; anything less and they simply go elsewhere for their fix. The government is on record as stating that they envisage returns of ca. 5% and will strive to ensure they do not go any higher by linking the price of PV modules to the FiT rate.

On the face of it this is a good proposal and should go some way to preventing the “Boom and Bust” that has beleaguered the industry. The mechanism has the potential to provide a sustainable and controlled future for the FiT.

In the long term, this is a positive for the industry, but short term – bearing in mind the skepticism and mistrust about the government’s attitude, and also bearing in mind the further cuts announced for July – you can understand why many are not cracking out the champagne just yet.

Solar panels in a low-tech setting: Breckenridge, Colorado

The belief is that Westminster is out of touch with where the industry is at, but most crucially and disappointingly, they fail to see where the industry can go. The Minister of State for Energy and Climate Change tweeted a couple of weeks ago that the Germans had just announced big cuts to their FiT scheme, implying that he was actually correct in pursuing the cuts here – blissfully ignoring the fact that Germany has had a Feed-in Tariff for the past decade, has a total installed capacity close on 25GW and operates on a completely different scale to the UK.

Under the new rates, the German government is proposing to pay €0.135/kWh for ground-mounted solar farms with a capacity of 10MW or less, and for rooftop installations that are 1–10MW in size. Germany is lightyears ahead of what is currently viable in this country.

There are, however, some reasons to be optimistic. The Chinese government last week directed the leading polysilicon and solar cell manufacturers to increase production, which should see prices continue to fall. That’s good news for consumers and probably bad news for non-Chinese manufacturers. China really does seem to be attempting to establish itself as the SPV equivalent of the Middle East. Continued downward pressure on price of SPV definitely looks set to continue in the short-to-medium term.

The great PV breakthrough should achieve one thing, however: SPV will at least now receive the recognition it deserves as a viable and high-quality alternative to fossil fuels. The SPV industry deserves recognition in Government energy strategy.

There is simply no reason why, if there is willingness on behalf of the powers that be, that by 2020 the UK cannot have the 22GW of solar capacity that government says it wishes to have.

Ross McGuinness, Area Sales Manager, Kingspan Insulate and Generate

Twitter: @rossmcguinness   Email: ross.mcguinness@kingspan.com

Spotlight on solar air heating

Andrew Brewster leads the Renewables Design Team for the CA Group – a specialist building envelope manufacturer and installer. In this guest post, he puts one of the lesser-known solar technologies under the spotlight:

Solar air heating is a proven technology that has been developed specifically for heating large spaces. With high-profile advocates including The Royal Mail, Marks & Spencer and Jaguar Land Rover, the technology is increasingly expected to become part of the sustainability strategy of those companies leading the charge for environmental responsibility.

Harnessing sunrays to heat large spaces

What is solar air heating?
Solar air heating works by harnessing the sun’s energy via a Transpired Solar Collector (TSC), or SolarWall®. The SolarWall® technology pre-heats fresh, outside air, which is then actively drawn into the building’s heating system, contributing considerably to a reduction in the need for fossil fuels.

The technology is 100% renewable and has the effect of dramatically reducing a building’s overall heating requirement, providing significant savings in energy consumption and carbon emissions.

SolarWall® in action
CA Group recently installed the world’s largest SolarWall® on a single building for Marks & Spencer, at the retail giant’s 80,000m² East Midlands Distribution Centre (EMDC) in Castle Donington. The 4,500m² Transpired Solar Collector is expected to reduce the building’s heating requirement by somewhere in the region of 30%, by generating more than 1,135,000kWh and saving over 256t of CO2 per annum.

The SolarWall® can be seen in action at the Jaguar Land Rover training academy in this video:

The benefits
The revolutionary solar air heating system has the lowest capital cost and the highest known efficiency of any active solar technology in the world (up to 80%), generating in excess of 500 Watts of thermal energy per square meter on a clear day [Dr. Chuck Keutcher, U.S. National Renewable Energy Laboratory (NREL)].

It also offers the quickest return on investment, with an estimated payback period of three years on new build and eight years on retrofit applications. So as well as being an excellent option from an environmental perspective, it is also one that makes good commercial sense.

Global recognition
SolarWall® has been available for almost 30 years and is used in over 35 countries globally. A number of companies have tried to emulate the system but, due to a lack of understanding and third-party testing, they have been unable to replicate SolarWall®’s level of system performance.

In the UK, as part of its ongoing development and accreditation, the technology has received the independent endorsement of five leading authorities: Oxford Brookes University, the Welsh Assembly, Cardiff University, BSRIA and BRE.

CA Group has seen a significant uptake in the technology because of the very tangible results it delivers. As awareness of the technology’s capabilities increase, the Group anticipates that solar air heating will become part of the sustainability strategy of more and more companies looking for cost-effective ways of making the biggest impact on their CO2 emissions.

CA Group’s interactive Renewables Guide offers further information on solar air heating and other renewable options geared towards the generation of power and heat for commercial, industrial and distribution centres.

• Find out more by downloading a copy of the CA Group’s Renewables Guide.
• Find, select and compare solar energy products on ESI.info.

Green covers from Down Under: an Australian designer’s summary of green roofs

Our ‘Australian Correspondent’, Mark Iscaro of First Angle, is in the process of specifying a green roof for a client’s building. In this guest post, he takes a closer look at the concept, components and benefits of living roofs.

San Francisco Academy of Sciences, by Osbornb on Flickr

“This blog will be focusing on a new Green Building initiative in Australia that is slowly making its way into the mainstream. Currently a growing trend around the world, the idea of having a green roof is gradually catching on. Even one of my own clients has finally given in and allowed me to put a green roof on their new building in Marysville.

So what is a green roof?

A green roof is a partially or completely covered roof containing a growing medium and vegetation. These are positioned over a waterproofing membrane and can include water retention, drainage and irrigation systems. There are two main forms of green roofing available in Australia: intensive and extensive, the difference being as follows:

1. Intensive roofs (roof gardens) contain over 300mm of plant growth and can include a wide variety of shrubs, grasses, tree species and even kitchen herbs. They are also more akin to a park or garden, with easy access for recreational purposes.
2. Extensive roofs contain less than 300mm of growing media, and so are generally lighter in weight. They are suitable for harsher growing conditions and require minimal irrigation, using hardy, low-growing plant and ground-cover species. These roofs can handle slopes up to 30°. Extensive roofs are usually only accessed for maintenance.

Commercial green roof installation, by Arlington County on Flickr

What are the benefits of green roofs?
• Reduce heating (by adding mass and thermal resistance value).
• Reduce cooling loads on a building by 50 to 90% (by evaporative cooling), especially if it is glassed in so as to act as a terrarium and passive solar heat reservoir: a concentration of green roofs in an urban area can even reduce the city’s average temperatures during the summer.
• Reduce stormwater run-off.
• Natural habitat creation, promoting biodiversity.
• Filter pollutants and carbon dioxide out of the air, which helps lower rates of diseases like asthma.
• Filter pollutants and heavy metals out of rainwater.
• Help to insulate a building for sound: the soil serves to block lower frequencies and the plants block higher frequencies.
• Increase agricultural space.

So now that you know a bit more about these wonderful creations and the benefits they provide, why not look at one for either your current home or perhaps your next project?

Note: Information was gathered from Wikipedia & Green Roof Technologies.”

Mark is active on Twitter, and details of his projects can be found on the First Angle design and planning website.

For more facts and figures on green roofs in the Southern hemisphere, Green Roofs Australasia is worth a visit. A good variety of extensive, intensive, semi-intensive and brown/biodiverse roofs can also be compared over at ESI.info. If you are looking to plant a facade rather than a roof, have a look at what’s available in terms of living walls and vertical gardens.

The relative sustainability of building materials – guides and sources

The trade associations, enthusiasts and lobbyists for different building materials are busy telling us how sustainable their material of choice is, and how it out-performs all others. Amongst the myriad claims, facts and figures, how can we establish which material is the most environmentally friendly?  And is that even the right question to ask?

Timber is a natural material and absorbs CO2 while it grows, steel is eminently recyclable, concrete is ideal for thermal mass construction, whereas bricks are durable and can be reclaimed.

Even if we discover which has the lowest embodied carbon, for example, we may not agree on what sustainability actually means. Are we talking about cradle-to-grave lifespans, economic viability, wildlife considerations, energy performance, aesthetic impact, recyclability – or even taking a holistic view of the building’s use and social sustainability within a local community?

In the absence of a unified framework of assessment and an agreement on relevant metrics, the debate will continue.

At the end of the day, each project needs its own, tailored assessment. A good designer will select from all options and choose what is fit for purpose, rather than become too attached – by habit or preference – to one material or another.

But in order to make that choice, we need a level-headed view of the facts available for each material, accompanied by real-life case studies. We also need to consult with people who are in the know about the different accreditations and codes, and can give an unbiased overview. Below are some sources that make a good start.

Codes and certifications: consultancy

• Mel Starrs, Associate Director at PRP Architects, specialises in sustainability and green buildings. Her Elemental blog is full of useful information.
• The CodeStore.co.uk has a directory of CSH consultants and assessors. Materials is number 3 on the Code’s list of 9 sustainable design criteria.
• Jennifer Hardi works for the BRE’s Low Carbon Future team and is also part of the technical support team for the Energy Saving Trust’s Best Practice Helpline.
• Bruno Miglio is a Leader of Global Materials Science at Arup. The team offers advice on the use of materials in engineering and architecture – from design to reuse or demolition.
• The BRE’s Green Guide to Specification assesses building materials and components in terms of their environmental impact across their entire life cycle.

Concrete

This is Concrete showcases sustainable construction projects and encourages project-based feedback, presenting case study evidence to support the sustainability credentials of concrete.

Sustainable Concrete has information on concrete production, performance and end-use, and provides indicators on materials efficiency.

MPA (Mineral Products Association) runs the Concrete Centre, which contains news, publications, webcasts, online services, advice and design tools.

Steel

The BCSA is the national organisation for the steel construction industry. Its website, SteelConstruction.org, has a section dedicated to sustainability. The BCSA’s Target Zero project “will generate costed solutions for structural steel framed construction that achieves highest BREEAM ratings and changes to Part L of the Building Regulations, meeting emissions reduction targets towards zero carbon by 2019.”

Timber

TRADA has a library of downloads that detail the sustainability of timber. The Association’s Technology Assessed scheme also helps establish whether a company’s literature gives a fair representation of the benefits and characteristics of a product or service – a useful tool against greenwash.

The Forestry Commission also provides comprehensive facts and figures on the timber trade.

Stone

All members of the Stone Federation of Great Britain have to comply with this Sustainability Statement. The Federation provides a Technical Advice Service for the commercial and domestic use of natural stone.

Stephen Critchley – a Master Stonemason in Central London – is a font of knowledge on ancient and modern uses of natural stone, giving talks, workshops and demonstrations.

The simplest view of the sustainability of natural stone – there is tonnes of it about and it lasts for a very long time – is outlined here by CED.

Bricks and blocks

Bricks, in the words of the Brick Development Association, are “a versatile and durable building material, with excellent life cycle performance, energy efficiency, high thermal mass and responsible manufacturing.” Its publications on the sustainability issues of bricks and brickwork are listed here.

Sustainable Build details the manufacture and use of bricks as a sustainable building material in this article, and also comments on stone vs brick.

What other sources have you found useful for determining the sustainability of specific building materials? Please leave a comment and let me know!

This post was inspired by an interesting conversation on Twitter with structural engineers David Sharpe and James Thomson.

Compare and select building materials on ESI.info

• Preblended concrete
• Structural and joinery timber
• Timber beams and joists
• Bricks
• Building blocks
• Building and walling stone
• Stone quarries
• Steel beams and columns

PassivHaus: the devil is in the detail

The PassivHaus concept is quite a simple one: create an airtight, super-insulated structure, install mechanical ventilation with heat recovery, address thermal bridging, and find yourself with a building that can essentially be heated by a hairdryer. However, as with most things, the devil is in the detail…

Here, I take a look at the following questions:

• What does a PassivHaus look like?
• What does a PassivHaus cost?
• What about air quality?
• Which products are used in a PassivHaus?
• What is it like like to live in a PassivHaus?
• What is the next big thing after PassivHaus?

What does a PassivHaus look like?

PassivHaus is really a design and build process, as opposed to a particular style of architecture. Whilst we may have preconceived ideas of a PassivHaus-certified building’s aesthetics, it could (at least in theory) look pretty much like anything – especially given that existing buildings can be retrofitted to PassivHaus standard.

100 Princedale Rd, Paul Davis + Partners

This was done at 100 Princedale Road – a Victorian house in a London conservation area – by Paul Davis + Partners and contractor Philip Proffit of Ryder Strategies Europe Ltd. This house was the first of its kind in the UK to achieve PassivHaus accreditation, meeting its target to reduce carbon emissions by 80%. (Granted, with the subject of the retrofit starting out as a drafty, four-story old house, there was plenty of scope for improvement.) In other words, a passive house can be anything from a large, new office building to a centuries-old, traditional house. Below are some examples:

Single-family residence in Brooklyn, NYC | Gregory Duncan

Eurogate Sozialbau, Vienna – Europe’s largest PassivHaus settlement? | Tiger46 on Flickr

Passive house office building in Austria | Tõnu Mauring

What does a PassivHaus cost?

The Footprint article on the Princedale Road Retrofit for the Future project includes an interesting breakdown of the cost / payback time / bills before and after completion, making a comparison between refurbishing to PassivHaus or Decent Homes criteria. The Green Building Store, in conjunction with Building magazine, has also provided a breakdown of costs for the Denby Dale PassivHaus in West Yorkshire.

What about air quality?

The more passive (or other enclosed, airtight and sealed) houses we construct, the more important it is that we keep monitoring and assessing the quality of the air circulated in these buildings. Are we avoiding moisture build-up? Is the air too dry? Is there enough of it? Will we see a concentration of emissions inside these buildings, over time, from the building materials used? What are the potential positive/negative effects on occupants’ health and well-being? Housebuilder’s Bible author Mark Brinkley experiments with air quality and CO2 levels in this House 2.0 blog post, relating his findings to PassivHaus standards.

To ensure a good level of fresh air supply, most passive houses are ventilated and heated by mechanical ventilation with heat recovery (MVHR). Heat from the warm air that is being extracted is passed to the incoming fresh air through a heat exchanger – with the result that heat loss is minimised and heating costs are reduced. Ducting is an integral part of this: “Marion Baeli, the architect on the [Princedale Road] project, stressed that in a retrofit with MVHR, the coordination of ductwork requires considerable design attention, and should be integrated right from the start.” (Footprint)

Airflex Pro suspended ceiling ductwork installation (Airflow Developments on ESI.info)

Which products are used in a PassivHaus?

The PassivHaus Institut provides a list of certified building components, products and systems suitable for use in PassivHaus construction. Presumably, as this concept gains popularity and awareness, the list will grow. We have already looked at ventilation. Other important components are energy-efficient windows, airtight seals and thermal insulation.

But of course, a component is only as good as its installation. As well as architects who know how to design a successful PassivHaus, and manufacturers who can make products suitable for this type of construction, we need contractors with the right skills and experience. (PassiveHouse Builders, Passivhaus/LCC, Passive Development and Viking House are some of the firms I have come across.)

Project Green Home, Palo Alto | Mark Hogan

What is it like to live in a PassivHaus?

Bill Butcher, the construction manager of the Denby Dale house, kept a 17-instalment diary during the building process. But what happens post-occupancy? How does the building perform, and how does it shape the lives and behaviours of its occupants? In a separate post, I have taken a closer look at the realities of living in a passive house.

What is the next big thing after PassivHaus?

In the absence of a unified, international environmental standard for buildings, there is a certain amount of ‘competition’ between the different accreditations. There is no shortage of acronyms to choose from, and there are almost as many opinions on which accreditation makes the most sense as there are design-and-build professionals. (For a sensible take on PassivHaus vs the Code for Sustainable Homes, see “The Bout of the Decade” by Sustainable Homes.)

Andrew Holt heads the practice Architectopia in Norway, and also runs a course on sustainable architecture. He has worked extensively on PassivHaus developments. In an Arkitektnytt.no article, he talks about what the next big thing after PassivHaus might be. Mentioning BREEAM, zero-emission housing and “plus houses”, Andrew emphasises the importance of tailoring the standard to the individual project, using different tools to come up with a package that is fit for purpose. He comes to a refreshing conclusion (my translation):

What follows ‘after’ the PassivHaus standard should be a variety of different possibilities, so that our ambitions are based increasingly on the individual project and its local climate and conditions. This would facilitate greater innovation, creativity and cross-disciplinary co-operation. This approach demands a high level of competence within the project team.

An understanding of what the PassivHaus standard is, is a prerequisite for high-quality construction within the energy-efficiency sector. An understanding of what the PassivHaus standard isn’t, is a prerequisite for moving forwards.

PassivHaus office in Langenhart | Train.bird on Flickr

How to design a Passive House

If you are looking to get started in Passive House design, you probably already understand the concept, but if not, first take a look at The Realities of Living in a Passive House, where the theory and the reality are explored.

Below are some more useful links and resources for Passive House design, ranging from the planning and design side, to the fully realised, bricks-and-mortar (or should that be insulation-and-seals?) side of things.

The concept
• Mark Siddall of Devereux Architects explains how simple the PassivHaus concept is and why it ‘is arguably THE low energy, low carbon design standard’.

Specification
• BRE provides a simple comparison between the outline specification of the PassivHaus standard and UK new-build common practice. Notice the wide gap.
• Passive House Planning Package – a clearly structured design tool that can be used directly by architects and designers.
• The Passive house Construction Check List from the German PassivHaus institute makes it easier to reach certified passive house standards by listing the most important steps in the process, and particularly draw the attention to the quality control process that must accompany the passive house construction process.

Certification
The standards are voluntary but rigorous.
• BRE oversees the PCScheme (PassivHaus Certification for Certified Designers and Consultants).
• Three key tests are carried out- the first being an initial energy calculation carried out in the Passive House Planning Package by a passive house designer, resulting in a passive house assessment report.
• A blower door test in the US, sometimes referred to as pressure testing / air permeability testing in the UK. (more info from a UK provider of PH testing services)
• The final quality checks by a qualified PH Certifier, after which the project is certified as an approved passive house.

image courtesy of BASF. Neopor® insulation used in Hudson Passive House by Dennis Wedlick Architect LLC

Organisations
• The Passive House Institute in Darmstadt, Germany, founded by PassivHaus co-originator Professor Wolfgang Feist.
• BRE UK Passive House hub
• International Passive House Association.
• Passivhaus UK, part of the BRE.

Other resources
•The Passive House magazine
•PassiPedia is a website dedicated to PH definitions, technical details, knowledge, news, performance stats, residents’ experiences etc.
•Certified Passive house designer course

UK Projects
• Y Foel, passive house in Wales
• The Crossway Passivhaus, by Richard Hawkes and featured on Grand Designs. See also this article by the certifier.
• Tygh-Na-Cladach, the UKs first affordable passive housing, designed by Professor Gokay Deveci. Again, certified by SPHC.
• The Lime House at The Works, Ebbw Vale. A certified Passivhaus and part of the Welsh Future Homes Project. Further details on the BRE website

Solar power and feed-in tariffs

A sunny day after the endless wet of August got me thinking about solar power.

Solar Energy System - Jeremy Levine Design on Flickr

In April 2010 the government introduced a feed-in tariff (FiT) to encourage low carbon electricity generation, particularly by organisations not traditionally associated with electricity generation. In effect the government was paying a generous fixed price for electricity being fed into the grid from small-scale renewables projects.

– Anaerobic digestion
– Hydro
– Micro-CHP
– Solar PV
– Wind

In February 2011 the government announced it wanted to reduce the incentives for large solar farms, although by targetting installations over 50kW in size this included larger rooftop installations on public and private buildings, as well larger field sites.

A reduction in the feed-in tariff from around 41 pence/kWh down to 19 pence/kWh (or less) for schemes completed after the 1st August 2011 has now been implemented.