Integrating Daylighting with Task-Ambient Lighting for Enhanced Energy Savings in Office Spaces

Daylighting has been widely studied as a fundamental aspect of spatial illumination and energy efficient façade design. Effective installation and control of shading devices diminishes the adverse effects of prevailing climatic conditions on building envelope performance and reduces resultant lighting and cooling energy consumption. Task-ambient lighting as a free-standing approach has also been proven to reduce lighting energy consumption compared with typical general ambient lighting. This study estimates the energy saving potential of integrating daylighting through fixed external horizontal shading slats with task lighting. Spot measurements were taken in a test room to validate a daylight calculation program. Full year indoor work plane daylight simulations were performed for office spaces of different floor areas and varying window to wall ratios. Indoor daylight quality was assessed using the Useful Daylight Illuminance metric and three different task lighting schemes explored. Lighting energy savings of 10% to 90% were estimated under the three schemes in comparison to similar office spaces with common unshaded heat reflective glazing.

Towards the integration of personal task-lighting in an optimised balance between electric lighting and daylighting: A user-centred study of emotion, visual comfort, interaction and form-factor of task lights

Task-lighting is a well-known strategy to save energy by bringing light where it is most needed, providing adaptable localised light conditions of special interest in the current home-office context. Despite these benefits and in addition to negatively impacting biological rhythms, the generalization of backlit screens has made task lights less demanded, with screen users tending to accept significantly lower amounts of the illuminance standards. In parallel, the advantages of task-lighting may contradict the energy benefits of presence-driven lighting or blinds automation. This pilot experiment aims at evaluating the task light usage patterns and characteristic preferences for both paper and computer work from a user-centered perspective to provide guidelines in terms of luminaires characteristics. Thirteen participants evaluated three different task lights in both paper and computer conditions. Our results emphasize the role of the luminaire’s form factor, interface and lighting control characteristics, providing general recommendations on luminaire design.

An experiment of double dynamic lighting in an office responding to sky and daylight: Perceived effects on comfort, atmosphere and work engagement

The experiment was targeted to develop design strategies and methods by testing the complex interplay between the dynamics of daylight and electrical lighting in an office. The double dynamic lighting design concept is based on the idea of adding task lighting, with a directionality referring to the daylight inflow and a variation on direct/diffuse lighting and respective changes in colour temperature respond to sky conditions and daylight levels. The experiment was conducted in an office space at Aalborg University in Copenhagen from September to December 2019. Four participants moved in and worked in the office with four-week periods of respective standard static lighting as a baseline, and dynamic lighting. In a parallel mixed method approach with interviews and questionnaires, the dynamic lighting was compared to the baseline and to a control group. The results indicate that the dynamic lighting periods had a positive effect on visual comfort, perceived atmosphere and work engagement. The studies helped to develop the definition of five dynamic light settings. Seasonal changes, time of day, dynamic sunscreens and individual needs for task lighting can be implemented in future field experiments as additional dynamic parameters to meet individual needs and circadian potentials for double dynamic light.

Lighting Control in Patient Rooms: Understanding Nurses’ Perceptions of Hospital Lighting Using Qualitative Methods

Purpose: This study differs in its methodological approach from previously published research by interpreting qualitative results against existing literature to understand how nurses conceptualize medical–surgical patient rooms as productive settings in relation to lighting, as well as the ways in which nurses believe these spaces could be enhanced for patient satisfaction. Methods: Content analysis was used to interpret themes emerging from nurses’ subjective responses to open-ended items. Three of the facilities had older, traditional lighting systems; one had a contemporary framework. Results: A theme of environmental control over both overhead and task lighting emerged from data from all items. Although controllability was among the “best” lighting attributes, more refinement is necessary for optimal staff productivity and patient satisfaction. Daylighting was also considered to be among the best attributes. Control over light level via additional dimming capability for patients, as well as additional light sources, was prominent across the four hospitals. Unique to the more modern facility, trespassing of light was problematic for nurses considering the experiences of patients—even where modern models exist, more attention can be paid to the ways in which window shades, and light sources outside of rooms, penetrate spaces and affect users. Conclusion: The finding that nurses and patients desire greater control over the lighting in patient rooms is consistent with Ulrich’s theory of supportive design for healthcare and coincides with advances in lighting technology. Despite differences in the level of sophistication in lighting among the four facilities, control continues to be a primary concern for nurses.

Effect on nurse and patient experience: overnight use of blue-depleted illumination

BackgroundTypical hospital lighting is rich in blue-wavelength emission, which can create unwanted circadian disruption in patients when exposed at night. Despite a growing body of evidence regarding the effects of poor sleep on health outcomes, physiologically neutral technologies have not been widely implemented in the US healthcare system.ObjectiveThe authors sought to determine if rechargeable, proximity-sensing, blue-depleted lighting pods that provide wireless task lighting can make overnight hospital care more efficient for providers and less disruptive to patients.DesignNon-randomised, controlled interventional trial in an intermediate-acuity unit at a large urban medical centre.MethodsNight-time healthcare providers abstained from turning on overhead patient room lighting in favour of a physiologically neutral lighting device. 33 nurses caring for patients on that unit were surveyed after each shift. 21 patients were evaluated after two nights with standard-of-care light and after two nights with lighting intervention.ResultsProviders reported a satisfaction score of 8 out of 10, with 82% responding that the lighting pods provided adequate lighting for overnight care tasks. Among patients, a median 2-point improvement on the Hospital Anxiety and Depression Scale was reported.Conclusion and relevanceThe authors noted improved caregiver satisfaction and decreased patient anxiety by using a blue-depleted automated task-lighting alternative to overhead room lights. Larger studies are needed to determine the impact of these lighting devices on sleep measures and patient health outcomes like delirium. With the shift to patient-centred financial incentives and emphasis on patient experience, this study points to the feasibility of a physiologically targeted solution for overnight task lighting in healthcare environments.