30 July 2014

Retrofitting showcase on a Belgian high-school

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A show case performed in Liege, Belgium, demonstrates how to turn a high school into an energy efficient and comfortable learning environment

Energy consumption in the non-residential sector, such as public and industrial buildings, is typically about 40% higher than in the residential sector. The EU-funded BRICKER research project integrates so-called passive and active technologies to retrofit existing public buildings in Spain, Turkey and Belgium. The Belgian showcase of the project will transform two of the seven school blocks of a Belgian high-school called the Haute École of the Liège Province. Raymond Charlier, industrial engineering expert attached to the Liège Provincial Building Service (SPB), tells youris.com about the challenges of implementing retrofitting in such a showcase building.

What kind of preparation does a building need to undergo before being retrofitted?
There are several major works phases to be conducted on the buildings of the Haute École of the Liège Province. A first public decision concerns the renovation of the curtain wall for the primary facade of the first block. A second covers the insulation of the facades and replacing the window frames of the first and sixth blocks. A third handles the roof insulation of both block one and six. These three interventions with passive technologies will increase the thermal efficiency of the building and diminish the need for heating energy.

The second phase will call upon active technologies. This involves installing several prototypes of decentralised ventilation with heat collections above the new window frames. A prototype for combined production of electricity and heating—which is based on what is referred to as a biomass fed cogeneration Organic Ranking Cycle (ORC) turbine system—is also part of the project. The choice for wood pellets or chips depends of an analysis of the supply chain and CO2-balance. Project partners in Spain and Turkey will probably opt for a mix of biomass and solar boiler or solar boiler only.

Two of the four public funding decisions will be cleared before the end of 2014. The last two will be decided upon early 2015. The total budget will be €2,831,920. Actual refurbishing is planned between June 2015 and April 2016.

What results do you expect?
The insulation is done with what is referred to as a polyisocyanurate (PIR) rigid foam that contains so-called nano-encapsulated phase changing material. Simulations suggest that a five centimetres-thick PIR-insulation could reduce the thermal transmission factor ten-fold, and thus limit heat loss. After the reconditioning of the building, the walls and the roofs are expected to achieve a thermal transmission factor further cut by a third.

The monolayer glass windows will be replaced by double-glazing with built-in solar protective layer that is nearly four times more energy efficient. The frames will be executed in aluminium with a thermal bridge to limit heat losses. Above some window frames, a decentralised ventilation unit with heat exchanger will regulate the incoming flow of fresh air while the heat from the outgoing air flow will bring it up to temperature, increasing comfort and efficiency even further.

The retrofit is expected to reduce energy consumption—both electricity and natural gas—with a view of cutting back on the emissions of greenhouse gases. The combined production of electricity and heat and the drastic reduction of our heating needs will diminish our electricity demand from the grid by 86 % and reduce gas consumption for heating in blocks one and six by 75 %, according to the preliminary estimations. The building is expected to scale from an E class energy level to B class. We expect savings of up to €211,000 a year resulting in a return on investment within a little over seven years.

Is such approach due to be replicated in other buildings?
The Liège Province has over one hundred buildings with some 450,000 m² of offices, schools, museums, etc. Many are similar to the showcase buildings dating back to 1968. All have a great potential for renovation and energy savings. The first decisions are expected early 2015. The project ends in 2017. After verifying our calculations on the efficiency of these new technologies a final report will be transmitted to the Province authorities that could initiate other major renovations elsewhere.

What are the major challenges?
The challenges are both organisational and technical in nature. The organisational challenge is to get the renovation works done while classes are running, as the school has about 1,000 students and 100 staff. The work is planned between June 2015 and April 2016. Affected classes will be organised in the remaining blocks in the school that are not being retrofitted, and in another school run by the Province. This will require tight collaboration and strict planning with the school and its users. The second technical challenge lies in implementing solutions fresh from the labs. We will be the first to test the added value and efficiency of these prototypes in practice.

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