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Growing our way out of climate change by building with hemp and wood fibre

Article by Mike Lawrence

From domestic housing to the Science Museum, plant-based construction materials cut reliance on scarce resources and build healthy, efficient and zero carbon buildings

How can buildings help with climate change? It’s all about renewables and “sequestered carbon”.

The Department for Business, Innovation and Skills’ 2010 report on Low Carbon Construction concluded that construction was responsible for around 300m tonnes of carbon dioxide emissions, which is almost 47% of the UK’s total. Of this, around 50m tonnes is embedded in the fabric of buildings.

Making one tonne of steel emits 1.46 tonnes of CO2 and 198kg of CO2 is emitted make one tonne of reinforced concrete. One square metre of timber framed, hemp-lime wall (weighing 120kg), after allowing for the energy cost of transporting and assembling the materials actually stores 35.5kg of CO2.

If we can convert plants into building materials, we are in a win-win situation. Plants use the energy of the sun to convert atmospheric CO2 and water into hydrocarbons – the material from which plants are made.

The plant acts as a carbon store, sequestering (absorbing) atmospheric CO2 for as long as the plant continues to exist. This CO2 is only re-released when the material is composted or burnt, and the great thing is that through replanting it you can re-absorb this CO2 annually, in the case of straw or hemp, or every decade or so in the case of timber, rather than the 300m years that it takes to recycle coal or oil.

Secondly, plant based materials can be used to make high performing building envelopes, protecting against external weather and making a building more comfortable, healthy and energy efficient to live in.

Not only can they be used as insulation materials, displacing oil-based alternatives such as polyurethane foam, but they also interact with the internal environment in a way that inorganic materials just can’t do.

This is because they are “vapour active”. Insulating materials such as hemp-lime, hemp fibre and wood fibre are capable of absorbing and releasing water vapour. This is doubly effective, because not only can they act as a buffer to humidity (taking moisture out of the air), but they also stabilise a building’s internal temperature much better through latent heat effects (energy consumed and released during evaporation and condensation within the pores of the material).

To build using hemp, the woody core or shiv of the industrial hemp plant is mixed with a specially developed lime-based binder. Factory-constructed panels are pre-dried and when assembled in a timber frame building, the hemp shiv traps air in the walls, providing a strong barrier to heat loss. The hemp itself is porous, meaning the walls are well insulated while the lime-based binder sticks together and protects the hemp, making the building material resistant to fire and decay. The industrial hemp plant takes in carbon dioxide as it grows and the lime render absorbs even more of the climate change gas. Hemp-lime buildings have an extremely low carbon footprint.

Building with hemp lime

Building with hemp lime. Photograph: University of Bath

In this way bio-based materials can be used to construct “zero carbon” buildings, where the materials have absorbed more CO2 than is consumed during construction. By applying PassivHaus principles (the voluntary industry standard for low-carbon design) to bio-based buildings, a building’s energy use once inhabited can also be reduced to minimal levels. This is a true “fabric first” approach, where the fabric of buildings passively manages energy consumption, rather than purely relying on renewables such as solar panels and ground source heating systems, which have a more limited life-span and the potential for failure.

I worked on a project recently for the Science Museum to reduce the high energy cost of archival storage. They needed to have large enclosures kept at a steady humidity and temperature to ensure that items ranging from the first edition of Newton’s Principia through to horse drawn carriages and even Daleks do not deteriorate. Normally this uses energy intensive air conditioning systems.

The three-storey archival store that the Science Museum built in 2012 using a hemp-lime envelope was so effective that they switched off all heating, cooling, and humidity control for over a year, maintaining steadier conditions than in their traditionally equipped stores, reducing emissions while saving a huge amount of energy.

Improved bio-based materials can also passively improve the internal air quality of buildings by interacting with airborne pollutants, removing them from the building. The new HIVE building – a £1m project funded by the Engineering and Physical Sciences Research Council – has been designed as a platform for research projects into this kind of sustainable construction. The HIVE has a purpose-built flood cell, which will also support research into creating buildings and building materials that are more flood-resilient – a valuable resource in these times of climate change induced adverse weather conditions.

Hive building

The Hive building. Photograph: University of Bath

Industry and government must also embrace the opportunities presented by bio-based construction materials to reduce emissions. Domestic housing is a key part of this. Good quality housing can be built out of structural timber with a bio-based insulating envelope using straw; hemp-lime, or other systems using wood fibre or other cellulose fibres.

With domestic housing high on the government’s agenda, it is time the construction industry recognised the economic and environmental benefits of bio-based construction materials and became less reliant on depleting resources including oil and steel.

This article was originally published in The Guardian 

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Can China’s 13th Five-Year Plan deliver more sustainable cities?

Article by He Quandong

China’s next five-year plan must turn the country’s urbanization ambitions into concrete, implementable measures, says the Energy Foundation’s He Dongquan

article image

Better public transport is likely to be a priority in China’s 13th Five-Year Plan (Image by Yuxuan Wang shows Beijing’s central business district)

As China’s policymakers mull the contents of the country’s next Five-Year Plan, chinadialogue asks a range of contributors what they would like to see in the development blueprint.

In March China published a new urbanisation plan for 2014 to 2020. How this vision is implemented through the 13th Five-Year Plan will determine what China’s cities look like in the years ahead.

There are a number of points in the plan worth noting.

The overall approach to sustainable cities is excellent. It calls for urban space to be optimised through public transport, high-capacity infrastructure and mixed-use development. These ideas are closely linked to China’s energy-saving and emissions-reduction needs.

New concepts include: transport-oriented development, mixed communities,urban growth boundaries and intensive urban development. These point towards fresh approaches to city building as planners seek to waste less on unnecessary infrastructure, shift patterns of behaviour, introduce systems to support public transport and change the emissions status-quo.

As well as greater use of low-carbon technology, new energy systems, smart cities and energy and emissions saving, the new plan calls for industrial land to be reallocated to encourage the circular economy. This recognises that, as China has urbanised, the efficiency of land-use has been low.

Also download our special journal: Reimagining China’s cities

Next we need to wait and see how the 13th Five-Year Plan turns these ambitions into concrete policies and implementable measures, and how it coordinates action across different government departments.

Another change is a new emphasis on the role of small cities. In the past, Chinese urbanisation policy looked to major hubs, but now the government recognises that a spread of smaller cities is needed to resolve economic and social issues. This will require changes in land ownership, government finance and taxation and the hukou system, in order to allow for a new phase of urbanisation, distinct from a past model dependent on GDP growth and government land sales.

The document also stresses that China’s urbanisation plans must be both feasible and properly enforced. Planning laws introduced in the past decade have supported the idea of “three plans in one”. This is the idea that content common to economic and social planning, urban planning and land-use planning should be carried out via a single process. The hope is that this will produce more scientific and feasible proposals which, crucially, are more likely to get implemented. In line with this approach, the regional plans proposed in this new document will include the housing authorities, the development and reform authorities and land authorities – going much further than the existing system run by the housing ministry.

I expect at the overall level the 13th Five-Year Plan will focus on solving issues faced by migrant workers, the hukou system, and coordination across different planning systems. Urban low-carbon development is likely to be covered at the level of specific plans, with the focus being coordination across different sectors.

The combined planning mentioned above is mainly happening at the local level: coordination mechanisms between the Ministry of Land, Development and Reform Commission and the Ministry of Housing are not yet in place. If we want better quality planning then the 13th Five-Year Plan needs to resolve this issue.

This article was originally published in China Dialogue

The newest Passive House building

Courtesy of 

Setting new standards of sustainability through the design of the Passive House “Bruck”,Peter Ruge Architekten’s project is a model apartment complex, consisting of 36 one room staff flats, 6 two room executive suites and 4 three-bedroom model apartments currently being built in southern China. With a 95% energy savings over that of a conventional Chinese residential building, the project is the first housing of its kind to be realized in the countries damp, warm, southern climate. Construction just began last month and is expected to be completed within the upcoming months. More images and architects’ description after the break.

Courtesy of Peter Ruge Architekten

This design approach plays a central role in the future strategy of recognized Chinese real estate development group Landsea.  The company’s plans to establish a research and development center in  acts to test, improve and implement innovative, energy saving and sustainable building practices in China.

Courtesy of Peter Ruge Architekten

Peter Ruge Architekten planned model apartments so that Chinese families, interested in the benefits of sustainable housing, could be provided with an opportunity to temporarily reside in the building. Through this direct experience, prospective clients are able to gain their own understanding of passive house living has to offer, as the building demonstrates maximum comfort and quality of residence. This aims to reduce any prior reservations had towards the success of passive house design in extreme weather conditions.

Courtesy of Peter Ruge Architekten

The local climate has shaped the impression of the facade: triple glazed window units have been specifically used in all private rooms and common areas, whilst fixed sun shading elements protect the glass facade in the warmer half of the year. The closed areas of the highly insulated facade act to protect the building shell from intense sunlight through a screen of colored terracotta rods.

1st floor plan

Peter Ruge Architekten, together with their client Landsea, and in cooperation with engineers from the German Passivhausinstitut Dr. Feist, have achieved an important architectural milestone through the design of Passive House “Bruck”, and the successful introduction of sustainable and future-oriented passive house standards to the Chinese residential housing market.

Architects: Peter Ruge Architekten
Location: Changxing, Zheijang Province, China
Team: Peter Ruge, Kayoko Uchiyama, Matthias Matschewski, Jan Müllender, Alejandra Pérez Siller, Duan Fu
Structural Engineering: Shanghai Landsea Building Technology Co. Ltd
Mechanical and Electrical Engineering: Shanghai Landsea Architecture Technology Co. Ltd
Thermal Structural Physics: Passivhaus Institut Dr. Feist
GFA Building: 2,200 sqm
Duration: 2011-2013
Completion: 2013