Engineers Forum

Engineers must start rolling out solutions now if we are to meet the tough low-carbon targets in the timescales required. That was the strong message ICE director general, Tom Foulkes delivered to delegates at the Business Council for Sustainable Development’s 10th anniversary summit.

Held jointly with the World Business Council for Sustainable Development, the summit explored what a future, low-carbon world will look like by 2050, what new skills and new business models will be needed, and what commercial opportunities are likely to arise.

Foulkes said: “ICE was created in the early 19th century by a group of engineers dedicated to responding to society’s needs following the industrial revolution. Today’s summit will address a challenge of an even greater scale, identifying how we must move to a low-carbon world. Once again science, engineering, and business must unite to meet the greatest challenges of our time.

“For engineers, these are exciting times, with huge opportunities in offshore wind, retrofitting our ageing building stock, new high speed rail networks, and using “waste” as a raw material and source of energy. The time, though, for academic debate has passed. To deliver change in the timescales required we must start rolling out these solutions now.”

Foulkes explained how ICE is playing its part in preparing future engineers for the challenges they will face, through initial and continuing professional development, as well as focussing on developing low-carbon engineering solutions in all aspects of ICE policy and public affairs work.

Later this year the Institution will be publishing a major inquiry on low-carbon infrastructure and work is also being done to press government to create a political environment which supports business in delivering a low-carbon environment.

Anyone wishing to submit evidence to the inquiry can do so by visiting the ICE website.
Source: www.ice.org.uk

Thermal mass, particularly when used as part of a passive solar design strategy, is increasingly being used to reduce heating and air conditioning energy consumption and bills. Both benefits are of interest to housing associations wanting to build sustainable homes that reduce both their environmental impact and the potential for fuel poverty.

The ability of thermal mass to reduce overheating problems is increasingly recognised. Perhaps less appreciated is its ability to save heating energy when used in passive solar design (PSD). Consequently, it is possible for concrete, masonry and other heavyweight dwellings to exploit their inherent thermal mass on a year-round basis. During the summer, heat is absorbed on hot days, helping to cool the internal temperature and prevent overheating problems. The stored heat is then removed by night ventilation. During the winter, the thermal mass will absorb solar gains through south facing windows, and slowly releases the heat at night. This process is effectively the same as that which occurs on summer nights, the only difference being that during the winter the stored heat is beneficial, so windows and openings are kept shut to minimise heat loss. Shutters and blinds used to prevent overheating in the summer can also help minimise heat loss during the winter.

Useful levels of thermal mass are found in medium and heavyweight construction, which in practice is most easily provided by concrete in the form of blocks and precast or in-situ floors and panels.

The use of concrete often raises questions regarding its embodied CO2, which can be slightly higher than that associated with alternative materials, but in reality the difference is relatively small when compared to lightweight systems. And, when you evaluate this in whole-life terms, the operational CO2 savings provided by the heavyweight solution is actually much more significant over the long-term. This point can sometimes be overlooked in the drive to specify the greenest materials available, but should to some extent be redressed in the forthcoming revisions to Part L1 of the Building Regulations, which will take greater account of thermal mass in the Standard Assessment Procedure (SAP) calculation.
To establish the facts of embodied versus operational CO2, The Concrete Centre commissioned research to examine the embodied and operational CO2 emissions of a simple semidetached house built using a typical lightweight frame, with that of several heavyweight versions built using varying levels of thermal mass. The embodied CO2 for each option was calculated and thermal modelling was undertaken to see how each performed across the 21st century, taking account of the likely impacts of climate change. The results showed that a typical masonry house with a medium level of thermal mass, has around 4% more embodied CO2 than an equivalent lightweight frame construction, but that this could be offset in as little as 11 years due to the energy savings provided by its thermal mass. Increasing the mass through additional concrete elements, such as precast upper floors, resulted in a longer offset period, but ultimately led to the lowest whole life CO2 emissions of all the options, with a saving in CO2 over the 21st century approximately six times greater than the difference in its embodied CO2 when compared to the lightweight frame solution.

Due to the predicted increase in summer temperatures resulting from climate change, the lightweight home was found to need air-conditioning by 2021. This compared with 2041 for the medium-weight home and 2061 for the medium-heavy and heavyweight homes.

Thermal mass is of course only one of the steps needed to adapt homes to a warming climate. Effective ventilation and shading are also of great importance in all types of housing, particularly in the south of the UK where overheating is likely to be greatest. Traditionally, shading has not been a major feature of UK housing. However, this is likely to change, particularly if tougher overheating rules appear in the Building Regulations. There are many shading options, but the most effective at minimising solar gains are externally located, such as overhangs and louvered shutters. The latter has the advantage of also providing secure night time ventilation in the summer.

In addition to having a medium to high level of thermal mass the key design requirement for capturing solar gains during the winter is to locate a large proportion of the glazing on the south elevation, or within about 30° of south. This will allow the low winter sun to shine directly into the home, passing underneath any fixed external shading overhangs. There are no hard and fast rules for window size in passive solar design; the objective is to optimise solar gains during the winter without incurring summertime overheating problems. This typically leads to a glazed area that between approximately 20 and 40% of the façade area. Glazing on the north façade should be restricted to the minimum area needed for adequate daylighting, since over the course of a year this will have a net heat loss.

Incorporating these all design features can help to maximise a home’s year-round passive thermal performance thereby reducing both CO2 emissions and energy bills.

The potential of using a building’s thermal mass to reduce its ongoing heating and cooling energy requirements is being increasingly recognised. How to successfully realise this potential is often less understood but is explained in new technical guidance from The Concrete Centre.

Until recently, the use of thermal was often disregarded in favour of a largely services-based solution for the heating and cooling of buildings. However, the wish to reduce the on-going energy consumption of buildings both in terms of carbon dioxide emissions and energy bills has led to a re-evaluation of the contribution that thermal mass can help to achieve a more sustainable built-environment.

“Exploiting thermal mass so that it helps to reduce heating requirements in the winter and cooling requirements in the summer is not difficult. However, it does need to be considered at the outset of the design process when the building’s form, fabric and orientation requirements are being determined”, said Tom de Saulles, building physicist, at The Concrete Centre and author of the report ‘Thermal Mass Explained’. “Get it right and you can have significant energy savings and carbon savings over the life of a building with less need for expensive low carbon technologies”.

Thermal mass, in the most general sense, describes the ability of a material to store heat. For a construction material to provide a useful level of thermal mass it must have a high specific heat storage capacity, be of high density and have moderate thermal conductivity so that heat conduction is roughly in synchronisation with the daily heat flow in and out of the building.

Timber has a high heat capacity but a low thermal conductivity. This limits the useful heat absorption rate and so provides a low thermal mass. Steel also has a high heat storage capacity but it also has a very high rate of thermal conductivity which means that heat is absorbed and released too quickly for any meaningful thermal mass efficiency. Concrete and masonry, with their high heat capacity and density but moderate thermal conductivity offers a good balance. They steadily absorb heat and store it until the ambient temperature drops causing stored heat to migrate back to the surface from where it is released. Heat moves in a wave like motion alternatively being absorbed and released in response to the variations in day and night-time conditions.

“The absorption and release of heat enables buildings with thermal mass to respond naturally to changing weather conditions, helping to stabilise the internal temperature and provide a largely self-regulating environment”, explained de Saulles. “This action helps to prevent summer overheating and reduces the need for air conditioning. It can also reduce the need for heating during the winter by capturing and later releasing solar and internal heat gains”.

During warm weather, much of the heat gain in heavyweight buildings is absorbed by the thermal mass in the floors and walls thereby reducing the risk of overheating. This heat is then removed by allowing cool night-time air to ventilate the building. This daily heating and cooling of the thermal mass works relatively well in the UK as the air temperature at night is typically 10 degrees less than peak daytime temperatures during the summer.

“The benefits of thermal mass, which is well understood in warmer parts of Europe, will become increasingly recognised in the UK as climate change results in hotter summer temperatures”, said de Saulles. “As well as cooler internal temperatures, these benefits also include reduced heating bills in the winter as instead of purging the day-time heat gains with night-time air, the stored heat is allowed to radiate back into the building”.

For the winter, thermal mass works best when it is used as part of a passive solar design strategy (PSD). This approach seeks to maximise the benefit of solar gain in the winter, using thermal mass to absorb gains from south facing windows, as well as internal heat gains from electrical equipment, cooking and lighting. These gains are slowly released overnight as the temperature drops so helping to keep the building warm and reducing the need for supplementary heating. Applying simple passive solar design techniques can result in fuel savings of up to 10 per cent. This saving can increase to 30 per cent if more sophisticated passive solar techniques such as sunspaces are adopted.

“The need to design and build for higher levels of energy efficiency and to mitigate the effects of climate change means that the performance requirements of building materials continue to increase. Meeting these challenges requires a whole-building approach where the materials, structure and systems work in unison to maximise the building’s overall performance. The thermal mass of concrete provides a useful constituent of this whole building approach”, said de Saulles. “Efficient use of thermal mass used in conjunction with orientation, solar gain, ventilation and shading can do much to reduce the whole-life carbon footprint of buildings”.

Source: http://www.concretecentre.com/

Jonathon Porritt, Founder Director of Forum for the Future, has applauded the concrete industry for its initiative and commitment to become a leader for sustainable construction.

Speaking at the launch of ‘The Concrete Industry Sustainability Performance Report’, Porritt commended the industry saying that: “I am genuinely impressed at the progress that has been made and the quality of the leadership shown. The industry is to be congratulated upon the journey that it is taking”.

Forum for the Future has been working with the concrete industry to develop and implement a sustainability strategy. The launch of the first industry-wide Performance Report marks a milestone for the concrete industry. It examines the challenges being faced and provides a statement of achievement. Importantly, the report provides industry data across 14 performance indicators against which the concrete sector has committed to be benchmarked against and to improve upon.

The performance indicators are wide ranging and include the implementation of environmental management systems, reduction of waste and carbon emissions, improved energy efficiency and the provision of locally sourced materials. In addition, there are commitments to enhance the environment and create sustainable communities. The report will be followed up on an annual basis so that ongoing sustainability improvements can be measured.

To download the report, visit www.sustainableconcrete.org.uk

Engineering is a rigorous art. Without rigour, it is not engineering.
Some years ago, in a TV documentary, scientists were being asked about the future. Naylor, a Californian Nano-technologist said, “Scientists do not know about the future. It is better to look to engineers. Scientists investigate the way the world works and record their findings. Engineers take what we know and create new things”. Described in this way, taking what we know and creating new things, engineering sounds like an attractive career. What is more it includes industrial design, product design, architecture and many other design jobs. I like the definition.
Engineering is about listening, getting the idea across, operating the wheels of power and motivating people.These are not the images of engineering put across by career advisor’s and the profession looses out as a result.

What do we need to do?

We need to co-ordinate or bring together the multitude of initiatives and to ensure that the message is both right and put across in the right way. We need our university engineering departments to have a critical look at themselves, to change their image and to bring themselves into the 21st Century.
We should find out what ideas relating to engineering capture the minds of young creative people. I believe they are attracted to ideas such as designing, energy use, conservation, making, and entrepreneurialism. This is engineering. We should make it known. These days the discussion of complex issues is part of the curriculum young people are used to. We need to get them involved in the ‘engineering debate’, discussing the issues that interest them and lead them to careers as engineers.

We need to improve the computer based career guides, to bring in young people who like working with other people, creating, making life better rather than the present guides which are geared to encouraging interest only from select mathematics and physics stars. We need to gather interest from career orientated students who want to be engineers because they have an interest in people, in developing our world, touching the earth lightly and treating it as if we intend to stay, and in helping society.

Abstracts from: www.burohappold.com, article by Rod Macdonald “Engineers for the future”