Lund (Sweden) is a medium-sized university city with a research-intensive industry. The town dates back a thousand years, but the number of inhabitants has grown largely during the last century and a great stock of the buildings from the 1960s and 1970s now needs retrofitting. Almost 90% of the heat demand in the city is supplied by district heating, and the hospital and some office buildings are connected to a district cooling network. The Linero demo site district is a housing district where two blocks Eddan and Havamal consist of 28 three-level dwellings built in the early 1970s. Only 16 of the 28 buildings are including in the CITyFiED project. Buildings after the retrofitting have an energy performance that resembles new buildings.
Demo Site Expected Impact
After the one-year monitoring period (April 2018 to March 2019), CITyFiED achieved the following environmental and technical impacts in Lund demonstration site.
(TABLE UPDATE FOLLOWS)
The key measures implemented in Lund are:
Energy efficiency in buildings
Retrofitting of the building envelope
The studies realized on the buildings of Linero districts highlighted that the envelope of the blocks present a good state of preservation and does not need a radical renovation. However, some interventions were necessary to improve the energy performance of the buildings and reduce thermal losses. Consequently, the renovations were targeted at the elements in the building envelope that with potential to improve the U-value. The interventions on the building envelope were related mainly to the replacement of the openings such as the windows with the least performing characteristics, the balcony doors and the old curtain walls. Furthermore, the retrofitting actions included the insulation of the roof and the opportunity to glaze the balcony (optional).
These improvements of the building envelope make it possible to reduce the indoor temperature without negative effects on the thermal comfort of the tenants. In addition, radiator thermostats, adjustment valves and shut-off valves were replaced during the renovation achieving a further energy reduction.
Building services (HVAC and lighting)
The ventilation system has been improved in the buildings and air heat pumps have been installed into the heating and hot water systems.
During the renovation, the lighting in the building's communal areas was changed to LEDs in order to reduce energy use. Furthermore, presence control was installed in stairwells, cellars, entrances and gable ends. With presence control, use can be controlled so that no more energy is used than required by the tenants.
The retrofitting actions included the possibility to replace the bathtubs with showers in order to save energy for the production of domestic hot water (DHW). Furthermore, individual hot water metering and billing was introduced in conjunction with the renovations.
Energy systems integration
The district heating renovation consists of new pipes in the ground from a connection point in the existing grid to the buildings, six new substations in the buildings and the interior primary connection of the substations.
The district heating in the CITyFiED buildings is controlled by a smart heat building system. The system takes the control signal from the outdoor temperature sensor and adjusts it by considering the indoor temperature in relation to the outdoor temperature, the heating on the primary side (the grid) and the secondary side (the building) of the substation
Photovoltaics were installed during renovation on the roof of six buildings. The installation of photovoltaics was connected to the electricity system of the building. The electricity production primarily feeds the building and reduces the need of bought electricity. In case the production exceeds the consumption of the building, the excess electricity is sent to the grid.
Mobility & Transport
An EV fast charger was installed in the demo area in order to give the tenants easy access to quick and well-functioning charging infrastructure. The charger is configured in order to host one car for car-sharing and one other private car at the same time.
Lund demonstration site included ICT actions in order to validate and monitor the energy performance of the retrofitting actions at different level.
Building energy management system
The whole energy system was monitored providing information at district, building and dwelling level. The implementation of smart meters allows to register constantly the energy performance of the installations.
Power line communication
Measurements from the existing electricity meters in the CITyFiED area are collected on the power lines by power line communication (PLC). With an increase in photovoltaics and other local electricity production sources connected to the grid a new third generation power line communication was implemented and tested.
Monitoring platform and visualisation tools
The visualisation was also implemented on three levels: district, building and home level. Home level focuses on household electricity use. Building level includes electricity, heating, and local solar PV production. On district level aggregated use of energy is visualized in order to evaluate the energy use of the demo site as a whole.