qa jyrki- kesti ruukki

Jyrki Kesti talks steel, sustainability and ZEBs

Jyrki Kesti is Technology Director for Ruukki Construction – a provider of sustainable building and construction products and services.

As part of a series of Q&As, constructsteel is interviewing experts within the construction sector on aspects of steel’s performance and sustainability. Our first interview is with Jyrki Kesti of Ruukki Construction.

What is Ruukki Construction and what is your role there?

“Ruukki Construction is a provider of sustainable building and construction products and services in Europe. Construction has been undergoing change for some time and environmental awareness is now common. Ruukki has responded to the need to combine environmental considerations with high quality building products, providing the tools for our customers to achieve greater sustainability.

“The steel industry is adapting and making strides to reduce its emissions which will in turn influence life cycle thinking, which is growing in importance."

“I’ve been working at Ruukki Construction since 2001 and have been Technology Director for the past 10 years. I work primarily on R&D activities related to the internal performance of steel structures for roofs and walls. When I took on my current role, I switched my efforts towards efficiency in steel construction, with a focus on energy saving effectiveness and the design of single storey buildings. My work involves looking at building envelopes and looking to optimise solutions, as well as examining the European Commission’s building requirements.

“I’ve run some European research projects myself, looking at acoustics, energy efficiency and other specificities, but for the last two to three years I’ve been focused on wider sustainability issues, including whole life cycle thinking. As part of this approach we’ve been implementing new systems for monitoring behaviour.”

As someone who looks at building requirements and structural efficiencies, what major qualities does steel offer as a construction material?

“Steel has a number of qualities that make it an important material for the construction sector. Its strength-to-weight ratio is a key quality. It has high ductility for aesthetic design, and it is highly durable. It is also recyclable without losing any material properties, which is a key aspect for lifecycle considerations.

“Steel offers fast and reliable solutions from a project management perspective. Installation is easy as structures are bolted together. It is also possible to highly optimise the cross-sections and members of a design allowing for very efficient long span structures that have a high degree of flexibility.

“Within 30 years, it could be possible to effectively put all emissions related to buildings down to near zero.”

“Steel enables high levels of prefabrication, offering a number of advantages, including increased speed of construction. In addition, it boosts on-site safety as it allows for a highly controlled environment and organised systems. The quality of the final product is very high which allows for on-site problem solving and great reliability. In addition, steel solves problems related to weather conditions, providing high levels of moisture safety. Steel is also perfectly suited for use in dense city areas that have limited space for construction.

“A key aspect of steel’s performance is how well it works in conjunction with other materials. Composite construction allows for two materials to be combined, resulting in performance that is greater than the sum of their two parts. For example, steel’s high tensile strength combined with concrete’s compressive strength can create enduring structures. It is possible to utilise all available materials in construction as a hybrid solution, combining them to get the most out of their strengths and minimise their weaknesses.”

How well is steel able to deal with specific construction challenges related to acoustics, fire and corrosion?

“Acoustics are relevant for all building types, but particularly for civic or residential buildings. It is perfectly possible to create steel structures that perform well for occupants acoustically. For example, you can employ perforated steel sheet structures in combination with soft materials to achieve high acoustic absorption performance.

“Another key area is fire safety. There are many different options that steel offers in relation to this. Sheeting and intumescent painting can meet high levels of protection requirements, and in Nordic countries one-to-two storey buildings have sprinkler systems that can be utilised not only to prevent fires but cool steel structures during a fire. Steel itself is also inherently fire resistant, but in combination with other techniques can resist the effects of high temperatures.

“Tackling corrosion is highly achievable as coating technology has developed significantly and is now very well defined. It is always possible to design the right coating for any particular environment. There are also long-lasting solutions available to designers, such as weathering steel, which is used quite a lot in bridges, and COR-TEN steel cladding on buildings. This is steel which forms a protective outer layer of oxidised metal that requires no maintenance. It has a long service life, meaning that its life cycle costs and considerations are good.”

What contribution can steel make towards a more sustainable building and construction sector?

“In Europe, the energy efficiency of buildings is increasingly cost optimised. While this has led to a greater focus on carbon emissions during the construction phase, the biggest source of emissions is still in the use phase, particularly heating and cooling. Carbon footprints are at a crisis point, but there is a lack of clarity as their calculations don’t always take into account the same life cycle considerations. There needs to be an open debate about this subject as priorities have not been fully defined, but some European countries are developing national regulations on reducing carbon production in buildings.”

“For example, timber in its end-of-life phase is not a recyclable material and is often burned to produce energy, creating CO2 emissions. However, with its lower weight and lower carbon implications in the construction phase, timber can appear to have a lower footprint than other materials. Conversely, steel production is carbon intensive, but once it is made it can circulate forever and reduces the need for future virgin steel.

“However, in the steel industry we have a clear plan. For example, SSAB has announced that by 2045 steel production plans to be fully carbon free, which when combined with approaches that weight life cycle phases differently, will lead to a reassessment of its footprint.

What are zero emission buildings (ZEBs) and what role can steel play in improving sustainability during the use phase?

“It’s not actually very clearly defined what a zero emissions building is. Across its entire lifecycle, net emissions should be zero. This is done by compensating for energy use by producing electricity or some other means to make the building carbon neutral.

“A key aspect of steel’s performance is how well it works in conjunction with other materials"

“Ruukki Construction has looked at using steel solutions to help produce a near-zero energy building. This building design and construction required detailed management and cooperation, with a holistic framework that combined various approaches. Use of steel helped enable an optimised building envelope that ensured high levels of airtightness. This combined with energy efficient HVAC and lighting systems, integrated solar applications and renewable energy sources for heating and cooling, brought down costs and lowered energy use dramatically. Other sustainable aspects were related to the building envelope where, for example, the panel insulation had very high recycled material content.

“Within 30 years, it could be possible to effectively put all emissions related to buildings down to near zero.”

Construction is increasingly environmentally aware. What does this mean for the next generation of architects and engineers, and what role does education play in materials decisions within the sector?

“Architects are the forerunners of material decisions, but they need access to the right information to base these decisions on. It is vital that basic elements are the first step of a student’s education. Structural mechanics are critical – students must have a deep understanding of structural behaviours and then in turn they will understand requirements. In the Nordic countries, the timber industries have been marketing very heavily and this is influencing materials decisions. Students can accept solutions without applying life cycle thinking so this must take on increasing importance and be taught more thoroughly.

“The use of modelling tools has increased a lot during the last 20 years. Those programmes started in steel structures and there have been huge steps forward in building modelling. Previously, models were only used in the design and factory phases. Now these techniques are applied in the construction phase as well. In the future, those models will continue their life through the use phase. It is critical that universities and companies offer opportunities for students to practice with these types of building information models.”

What role do you see for steel in the future of construction?

“The steel industry is adapting and making strides to reduce its emissions which will in turn influence life cycle thinking, which is growing in importance. We need to look at regulations as there are enthusiastic governments and the construction industry needs to contribute to decisions that are being made. Due to these factors and its many inherent qualities, I am confident that the use of steel in the construction industry is only set to increase.”