CITyFiED Site Lund
Lund 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 number of the buildings from the 1960s and 1970s now need 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 focus of the CITyFiED project are 16 houses in the Linero district spread over 40,400 m2. The retrofitting aims to reach a higher energy standard with maintained affordability for the tenants. Simulations of the energy-efficient measures included in the retrofitting strategy were carried out during the first part of the project. They showed that the original final energy savings targets not only can be accomplished but will be surpassed.
The first round of analysis showed that the total final energy savings in Linero would reach approximately 58 kWh/m2/yr. This value is better than the project’s original target of achieving a reduction of 31%. Primary energy savings at the site have been established at 19% of the original primary consumption and greenhouse gas emissions are to be reduced by 26%. Four indicators for indoor environmental quality in the buildings were analysed – operative temperature, relative humidity, CO2 levels and the Predicted Percentage Dissatisfied (PPD) index to measure ambient climate dissatisfaction. None of the indicators show critical levels in the current buildings and no negative effect has been observed from the calculations of the renovation measures. At the heart of reaching these performance targets are the research, planning and efficiency of the extensive renovation strategy.
The overall gross floor area of 40 400 m² has been refurbished in the Lund demo site affecting 1150 people. The annual final energy saving estimate is 2343 MWh. The total CO2 emission savings estimate amounts to 404 tonnes per year.
Great efforts were invested in improving the living conditions (both indoor and outdoor) in the Linero district in an economically sound way so that the tenants can remain in the area. Frequent meetings with the tenants have been carried out to ensure high acceptance of the measures.
The Swedish partners have established structures for working together to safeguard the systemic approach that characterises the project. These are a steering committee ensuring a high-level awareness of the CITyFiED actions and methodology, a communications group to speak with a united voice and engage with residents, and collaborative working days.
*Information regarding the technical and financial performance will be available at a later stage.
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.
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.