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Occupant controlled lighting is known to present opportunity for energy savings1,2,3,4 and can increase occupant satisfaction with the lit environment5, 6, 7, 8, 9. Scale model and Laboratory studies suggest that the illuminance interval and the starting value provided to occupants to adjust from, have an effect on the illuminance settings chosen by the occupants 10. The illuminace interval limits the possibilities of choices and the chosen illuminances tend to be distributed in all parts of the illuminance interval. This results in the mean value of illuminance settings to approach the middle of that specific interval 11,12. The starting values act as anchors for the illuminance choices, meaning that low starting values tend to result in lower illuminance settings then high starting values6, 11, 12. The influence of illuminance interval and start value is considered in this case study on occupant controlled lighting in offices with focus on energy savings and occupant satisfaction. The case study was performed in a pharmaceutical company in Måløv, Denmark where the lighting installation was renovated in a two person office and a four person office in 2013. The fluorescent tubes were replaced with DALI controllable LED luminaires and each employee was given a task light on their desk providing 592 lx, U0 = 0.5 on the task area (60 x 60 cm2) and 87 lx, U0 = 0.2 on the surrounding area, when turned on. The lluminance intervals started from zero to the maximum of 50, 100, 200 and 500 lx with U0=0.5. The starting values were the minimum and the maximum of each interval and every interval with the different starting values was presented to the occupants in a randomized order for a total of one week. The CCT was 3000 K and the illuminance settings data was monitored online by collecting the DALI signals to the LED luminairs and the use of task light was registered by continuously measuring their power consumption. The test was performed from January to March 2014 and the weather conditions were mostly overcast sky. The occupants were informed that the lighting in their offices was being tested and at the end of each week they were asked to answer an online questionnaire about their satisfaction with the office lighting. They were further notified that they, at all times, were allowed to adjust the lighting in their office to their preference. One of the two offices reported the lighting system to malfunction when the 0 – 50 lx interval was provided, they were thereby provided with an interval of 0 to 100 lx in order to support their working environment. The adjusted illuminances for the high start values were 50 lx, 100 lx, 200 lx and 455 lx for respective maximum illuminance of 50, 100, 200 and 500 lx. The low start values resulted in illuminance settings of 50 lx, 83 lx, 163 lx and 193 lx. The energy use of the LED system is compared to the previous installed power of 80W for fluorescent tubes in each office. The illuminance settings led to 80% savings for the maximum 50 lx interval, 70 % savings for the 100 lx interval, 50 % savings for the 200 lx interval and for the 500 lx interval the savings was 50 % for a low starting value but the savings were negative by 17 % when the starting value was high. The occupants of the two person office only operated the task light when the interval provided a maximum of 100 lx, starting at a low starting value. The occupants of the four person office operated the task light 65% of their working hours when provided with a low starting value and 48% of the time when provided with high starting values. The average satisfaction ratings indicated that the occupants were most satisfied with the maximum 200 lx interval; this applies for both high and a low starting value. The interval with a maximum of 500 lx provided the most satisfied occupants and the most unsatisfied occupants.The results of this case study can be used as an argument for further exploring the potential that lies within occupant controlled lighting for energy saving and occupant satisfaction as the results from the limited amount of subjects in this study support the laboratory findings for occupant controlled lighting. Low starting values within a limited illuminance interval may provide satisfied user of energy efficient occupant controlled lighting.

This editorial introduces the 23rd volume of the International Journal of Sustainable Energy Planning and Management. This volume presents research on the robustness of energy modelling, firstly through an assessment of the accuracy of heat demand estimations compared to measured data, followed by an examination of assessment of the robustness of energy modelling relative to the results’ dependency on input time series. Subsequently, challenges to the integration of renewable energy are reviewed, followed by a case from Iran investigating a 100% renewable energy system for desalination. Finally, the issues of technology prioritization for energy efficiency purposes and the development of energy indicators are tackled. International Journal of Sustainable Energy Planning and Management, Vol 23 (2019)

The Danish energy system is undergoing a transition from a system based on storable fossil fuels to a system based on fluctuating renewable energy sources. At the same time, more of and more of the energy system is becoming electrified; transportation, heating and fuel usage in industry and elsewhere. This article investigates the development of the Danish energy system in a medium year 2030 situation as well as in a long-term year 2050 situation. The analyses are based on scenario development by the Danish Climate Commission. In the short term, it is investigated what the effects will be of having flexible or inflexible electric vehicles and individual heat pumps, and in the long term it is investigated what the effects of changes in the load profiles due to changing weights of demand sectors are. The analyses are based on energy systems simulations using EnergyPLAN and demand forecasting using the Helena model. The results show that even with a limited short-term electric car fleet, these will have a significant effect on the energy system; the energy system’s ability to integrated wind power and the demand for condensing power generation capacity in the system. Charging patterns and flexibility have significant effects on this. Likewise, individual heat pumps may affect the system operation if they are equipped with heat storages. The analyses also show that the long-term changes in electricity demand curve profiles have little impact on the energy system performance. The flexibility given by heat pumps and electric vehicles in the long-term future overshadows any effects of changes in hourly demand curve profiles. International Journal of Sustainable Energy Planning and Management, Vol 7 (2015)

Rising energy costs, anthropogenic climate change, and fossil fuel depletion calls for a concerted effort within energy planning to ensure a sustainable energy future. This article presents an overview of global energy trends focusing on energy costs, energy use and carbon dioxide emissions. Secondly, a review of contemporary work is presented focusing on national energy pathways with cases from Ireland, Denmark and Jordan, spatial issues within sustainable energyplanning and policy means to advance a sustainable energy future. International Journal of Sustainable Energy Planning and Management, Vol 1 (2014)

It is often highlighted how the transition to renewable energy supply calls for significant electricity storage. However, one has to move beyond the electricity-only focus and take a holistic energy system view to identify optimal solutions for integrating renewable energy. In this paper, an integrated cross-sector approach is used to determine the most efficient and least-cost storage options for the entire renewable energy system concluding that the best storage solutions cannot be found through analyses focusing on the individual sub-sectors. Electricity storage is not the optimum solution to integrate large inflows of fluctuating renewable energy, since more efficient and cheaper options can be found by integrating the electricity sector with other parts of the energy system and by this creating a Smart Energy System. Nevertheless, this does not imply that electricity storage should be disregarded but that it will be needed for other purposes in the future. International Journal of Sustainable Energy Planning and Management, Vol 11 (2016)

In the transition towards 4th generation district heating (4GDH), supply and demand side measures have to be coordinated better than in previous generations of district heating (DH). Building’s heat demand has to be reduced, and heating installations as well as consumer behaviour have to be adapted so as to be compatible with and support lower network temperatures. It is therefore necessary to investigate and understand how consumers can be meaningfully and strategically included in the transition towards 4GDH. This paper provides a literature review of the consumer levels role in 4GDH in the transition towards 100% renewable energy systems. Current literature of 4GDH have been investigated to identify the connection and involvement of consumers in the transition. Even though consumers within the existing building mass have a large role in the transition in terms of heat savings and instalment of energy efficient technologies in the buildings are almost none of the scientific literature addressing how these actions should be implemented at consumer level. From the results of the analysis it is recommended that further research should investigate how to strengthen the coordination between supply and demand sides in order to secure the right initiatives are implemented in the right order. International Journal of Sustainable Energy Planning and Management, Vol. 29 (2020)