The recommended solution using Airmaster decentralised ventilation units had the best overall economy over a 15-year period.
Mike Vinge, Engineer and Project Manager, Ekolab.
Improving the indoor climate was an important part of the renovation and therefore weighted highly in the choice of solution. The recommended solution scored top marks on all indoor climate parameters. The parameters were studied for an indoor climate with 28+2 people and that the solution could, among other things, maintain a CO2 level below 900 PPM.
The recommended solution had the best overall economy over a 15-year period. The investment itself was not the lowest, but it was the best solution in terms of the overall economy by virtue of its lowest energy consumption.
Both the quality of the indoor climate and the energy bill will be improved greatly by effective demand management. The ventilation units are controlled by the CO2 level, so they switch on when the room is in use and switch off again when the room is vacated. This means that no unnecessary energy is wasted in rooms that do not require ventilation.
Day-to-day operation is controlled by Airmaster’s built-in automation, which has been integrated in the school’s BMS system via BAC-Net IP. Service personnel are notified when it is time for a service and filter change.
With decentralised units, there are more filters to change than with centralised units, but no valves to be checked on the duct system. There is less impact in the event of stoppages with decentralised units, and there is greater flexibility, as well as far lower energy consumption. This was also included in the analysis.
The renovation project started in the summer of 2016, when the building itself was dismantled and renovated during the summer holidays. Work on the heating, ventilation, new ceilings and lighting took place after the holiday while the school was in use.
Four temporary classrooms were established at the school, ensuring that there were four “makeshift classes” to make use of at all times. This way, four classrooms could be renovated at a time, without having to rehouse pupils.
Other topics included in the analysis were "Buildability and durability". This included analyses of cable racks and fire and smoke protection.
Aarhus city council decided, as part of its budgeting for 2013, to initiate investment in systematic energy renovation of the municipality’s building stock. The City of Aarhus aims to realise a fundamental reduction of CO2 emissions through economically viable energy savings. At the same time, the aim was to gain significant side benefits in the form of a better indoor climate, for example. The renovation projects go under the heading of “Aa+ Energirenovering” (Aa+ Energy Renovation) and are one of the City of Aarhus’ own contributions towards achieving the CO2030 objectives.