Finland's first near zero-energy hall

Near zero-energy hall

Finland’s first near zero-energy hall for retail space and commercial premises was completed in the spring of 2015 in Hämeenlinna. Built on the campus of Häme University of Applied Sciences (HAMK), the hall is being used for research, development and teaching purposes by the university, Ruukki Construction and HAMK’s Sheet Metal Centre. The purpose of the construction project was to show that a hall exceeding today’s strict energy-efficiency requirements by 30 percent can be built for profit.

Managing the whole enables optimisation

The new structure was designed and realised to enable economic use of the building and optimisation of construction solutions. Optimisation means selecting solutions based on investment outlays, additional usage costs and future savings. In other words, choosing energy savings or yields that generate the best financial revenue during the lifespan of the building. For instance, when considering the full lifespan of the building, renewable energy gives a higher return than thicker insulation in the roof and walls. As another example, why invest in 20 cm of additional insulation on a roof when, for the same price, it is possible to invest in solar energy, which brings the greatest financial returns over the entire lifetime of the building? Financial return refers to savings measured simply in money.

Energy efficiency standards revolutionise construction techniques

Energy efficiency has risen to the same level as construction quality and economy as one of the most important factors steering construction. Investments in energy efficiency have already been made, particularly in residential and office construction. The guiding element in the product development at Ruukki Construction has been to develop products and construction solutions that improve commerce, industry and logistics through energy efficiency. In Ruukki’s concept, buildings must be designed and realised as complete entities – not split up into subareas. This approach is almost contrary to present-day construction, in which design and realisation are distributed to several operators without the complete entity being fully managed. The realisation of commercial, industrial and logistics buildings should also be steered by, for instance, so called alliance agreements, in which involved parties would be bound to share the responsibility of realising buildings in accordance with customer requirements (in addition to technical cooperation).

More multifaceted requirements targeted on construction, such as economy, quality, energy efficiency and environmental friendliness, also seem to raise a demand for planning and managing entities as a whole. If the requirements are met, the construction sector will have to change its operational model.

The foundation and roof work together

On the roof of the hall’s technical area, a total of 24 Ruukki Classic® solar collectors have been installed. The Classic® solar system integrates with the roof. Ruukki Construction energy piles have been incorporated in the foundation to use renewable energy to heat the building.

Solar collectors accumulate thermal energy from the Sun during the summer and transfer it to the soil through the energy piles. The soil acts as a seasonal thermal reserve, much like a battery. Beneath the building, a clay layer extends to a depth of 11 metres. Clay has a greater thermal storage capacity than, for example, gravel. In the winter, the piles transfer energy from the soil to heat the building. The building’s basal area totals 1,500 m2, and 64 energy piles have been used in its foundations.

The energy stored in the soil is used to heat the building with the help of heating pumps. A separate well drilled into the rock is employed for cooling. The heat conducted to the soil during summer intensifies the power produced by the heating pumps.

Facade that generates electricity

Solar power is also used in the outer walls of the building. Our Ruukki® on-wall solar panels, which generate electricity from the light of the Sun for the building’s network, are installed on its Southern facade. A total of 40 of these PV (photovoltaic) panels are found in the wall. The entity includes, in addition to the panels, mounting systems and electronic components as well as grid connections.

Ruukki’s panels, which utilise the light of the sun, were installed in the building on a total of 61 m2 of its surface area.

Windows towards the light

The sizes and directionality of the building’s windows have been optimised for energy efficiency. The large windows are aimed South and West. The need for artificial lighting is reduced by the windows, due to their directionality and surface area. Traditional large windows bring light in – but also conduct heat out. In this building, the glass windows facing south have been replaced by cell windows made of polycarbonate. These “daylight” windows isolate heat well – the warm rays of the sun during the summer do not heat the premises. During periods of bright daylight, light coming through traditional windows in indoor areas causes glare. Instead of this, daylight windows distribute light into the premises in a pleasantly even manner without glare, and blinds are not needed.

The main purpose of the windows were to improve working conditions, but based on the first experiences it was noted that the windows create pleasant and evenly distributed light into the space and that we hardly need artificial lighting during light seasons. We carried out lighting simulations into the spaces where large windows were installed, and the results were surprising: It's possible to save more than 50 % in yearly lighting energy if daylight sensors would be installed and the lighting level would be adjusted by available daylight. The target level for illumination was 300 LUX but the results were almost as good in a  500 LUX case.

On the North wall of the building, Ruukki Construction energy panel system windows, forming a dense structure with the panels, have been incorporated.

Savings from dense structures


Dense, energy-generating walls

The shell of the building walls and roof has great significance for its energy efficiency. For this reason, the outer walls of the building have been fitted with Ruukki’s energy panel system, with airtight panels and seals between the panels, plinth and roof. The energy panels reduce heating expenses, which in turn reduce building lifetime costs and carbon dioxide emissions. The rise in the energy class also raises the value of the real estate. The energy panels are sandwich panels with an insulating layer between two thin steel sheets. Five colours of Ruukki energy panels in the building were used to a total of 1 520 m2. For the first time, module molding of various colours was incorporated between the panels, by which extensive variety in the facade was obtained. The thickness of the insulation in both the wall and the corner panels is 23 cm.

Heating and cooling from the roof

New types of radiation-based heating and cooling profiles developed by Ruukki Construction have been installed in the building. The profiles have been affixed to the underside of the ceiling. Their generated radiation either cools or heats the interiors, depending on the season and the desired indoor temperature of the building. A new type of indoor heating and cooling system reduces energy consumption caused by ventilation. Airflow is required only for the influx and removal of fresh air – not actually for heating the premises. The new control system reduces temperature variations on each floor in the hall, increasing the usage comfort of the hall considerably, which improves well-being at work and productivity.

Impressive facade

The facade of the building is built with Ruukki energy panels in five individual colours. Some panels are micro-profiled, and some have even surfaces. In addition to elements that generate solar electricity, an impressive look has been obtained for the facades with Ruukki Expression™ and Ruukki Forma™ products.

In the west gable of the building, Ruukki Expression™ has been installed on approximately 240 m2. This product enables any kind of graphic image or pattern to be attached to the facade. In this energy-efficient building, a cloudy sky pattern illustrates the building’s positive take on the environment. Along the southern facade, Cor-ten steel lamellas have been mounted in the facade panels of the technical area. Ruukki Forma™ enables the mounting of Ruukki’s facade products to panels, and a more multi-dimensional look to the building. In this hall, tailor-made Cor-Ten rainscreen panels have been incorporated, covering an area of about 90 m2.

Real-time data

Instruments and sensors have been installed in the building structures to measure the functioning of the building’s structures as well as the mechanical and electrical solutions, and to verify its energy efficiency. Collected data will be utilised in real estate maintenance to adjust the building to work as planned. The data can also be applied in product development.

In addition to the energy efficient construction solutions mentioned above, Ruukki Construction has supplied the hall’steel framework, along with its design work, plans and installation.

Video interviews about the project

Experiences from building the near zero-energy hall

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Ruukki's energy efficiency work and the first near zero-energy hall

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Using daylight in buildings

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Blog posts

More information about the near zero-energy hall

Petteri Lautso, Sustainability Director, Ruukki Construction
Tel. +358 40 5685 507,

Jyrki Kesti, Technology Director, Ruukki Construction
Tel. +358 20 592 8107,

Pertti Puusaari, Rector, Häme University of Applied Sciences
Tel. +358 400469 605,

Jarmo Havula, Director, Sheet Metal Centre, Häme University of Applied Sciences
Tel. +358 408241 955,

Visit the near zero-energy hall

You’re welcome to visit the building to experience the near zero-energy hall! Ruukki's Technology Centre is located in the same building and is open for visits. Contact:

Jyrki Kesti, Technology Director, Ruukki Construction
Tel +358 20 592 8107,