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Towards energy efficiency – from U-value measuring to smart building

The primary function of a building envelope is to provide protection against weather and to enable satisfactory indoor climate conditions. Temperature control requires always use of energy and when talking about energy efficiency in construction, subject is usually energy used for heating or cooling. The path towards energy efficiency has been a story of lessons learned.

Construction is heavily regulated industry. Target of the regulation is of course to ensure safety and quality. Challenge in regulation is that all requirements need to be easily measured. Therefore in the past, energy efficiency targets have been guided by setting limits to building envelopes heat insulation properties. Parameters like U-value are easy to measure and prove – as well as easy to use in energy efficiency calculation in design phase.

Lesson learned – don’t forget the basics of building physics

Drawback in such approach is that while concentrating only on one parameter, you easily forget to control the entity – the entire building in this case. Early 70s proved this case. During energy crisis new improved insulation requirements were set to improve tightness of the envelope. This was done without paying attention enough to i.e. controlled ventilation especially in small houses. This led to many moisture and mould damages in envelopes. Lesson learned – building physics should not be forgotten.

At Ruukki we have been working with energy efficiency since the very starting of construction business. First targets of course were fulfilling all local and global regulation with our panel portfolio. About ten years ago more targeted R&D roadmap for energy products was created. The target was to get ready to tightening regulation and to find possibilities to improve the properties of the building envelope.

Lesson learned – don’t forget to control the whole building

Quite soon it was clear that focusing only on insulation and improvements of envelopes U-value, will not bring economically feasible results. If primary target is to reduce heating energy consumption in building, you need to get control over the whole building. This led to the development of Ruukki energy panel system that clearly improved air-tightness of the building envelope and enabled control over energy performance of the building.

Having control over the whole entity means that the design part of the process is more demanding and more complicated. In the future the complicity in design and also in building use will only increase. Good thing is that also tools enabling better control are developed and will fast become cheaper, so the design phase will become more routine.

Lesson learned – regulation boosts energy saving actions

Talking about targets and regulation; EU’s 20/20/20 climate and energy goals by 2020 mean targeted 20 % reduction of energy consumption, 20% reduction of greenhouse gas emissions (compared to 1990) and that 20 % of energy is produced by renewable sources. Goals will be implemented by various actions. Tools used are for example energy efficiency programs, standards and increasing energy efficiency requirements for buildings.

So construction is heavily regulated, but also pretty straight forward cost driven business. Sustainability pioneers are quite rare, even though current technology and solutions would enable exceeding regulative levels with relatively small extra cost. So money talks. And to boost positive development, we end back to regulation.

As buildings count for about rough one third of global energy consumption, construction has a key role in energy saving. Concrete target set according to new energy performance of buildings directive proposal, is that all new buildings are to be ‘near-zero-energy’ by 2020. In near-zero-energy building, local renewable energy production covers most of the need for purchased energy.

This target in mind Ruukki’s construction solution portfolio already covers geothermal heating solutions integrated into steel piles, building integrated PV façade solution as well as solar thermal systems integrated to roofs.

The EU 2020 target will boost the usage and development of solutions for local energy production. In the near future smart buildings will control and guide also the users towards energy efficiency. But that is yet another story to be told and lesson to be learned.

Pekka Roivio, Director, Products and Services, Ruukki

Green building

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