Energy reductions achieved by the ZenN demonstrators
At a general level, the monitored results have shown a reduction of 26-67 percent of building energy loads referring to final energy in the retrofitted buildings. This displays the general great potential to reduce energy loads in similar neighborhoods.
The renewable energy share is higher than 90 percent in Grenoble where the local district heating is fed by biomass. In the case of Oslo and Malmö, the local photo voltaic (PV) panels’ electricity production have contributed to 7.5 percent and 4.3 percent of the total energy demand of the buildings. These PV panels’ contribution in a sole electricity perspective is more significant. In the case of Mogel, the area of flat solar collectors installed on the rooftop should be able to cover 30 percent of the DHW load, as initially expected. However, the distribution side needs optimization, why the monitored final renewable share of the Domestic Hot Water (DHW) demand is lower at this point.
Proper execution, implementation and maintenance of the solutions
The proper execution and implementation of the designed solutions is essential to achieve the expected results in building energy loads. Concerning active technologies, besides the implementation, commissioning is of high relevance in order to achieve the expected results, including the settings and control functions of the operation mode of all active systems. Also periodic maintenance of active technologies is important in order to keep systems functioning properly. The integration of the systems into Building Energy Management System (BEMS) for management and proper operation of buildings has been perceived as one of the key issues in order to reduce energy use of buildings.
User behaviour is determinant to meet energy targets
Also, the energy behaviour of the building tenants is determinant for the level of energy efficiency that is possible to reach. This is examplified e.g. in Arlequin 40 and Mogel, where building tenants have control of the space heating indoor settings through access to boilers and the hand regulating valves, called “thermostatic valves”, at the inlet of heaters. Training actions to the tenants and staff on how to operate their buildings can bring further energy reductions in these neighbourhoods is important in this perspective.
Valuable learnings obtained from the monitoring platforms
Overall, the detailed monitoring platforms installed in the four demonstration sites of ZenN have verified that achieving NZEB in existing buildings is possible. The monitoring platforms also function as a valuable tool to identify potential operation problems, to optimize system operation during commissioning and to identify areas of further improvement concerning future projects of nearly zero energy neighbourhoods.