Control of flowering in the perennial model, the woodland strawberry (Fragaria vesca L.), involves distinct molecular mechanisms that result in contrasting photoperiodic flowering responses and growth cycles in different accessions. The F. vesca homolog of TERMINAL FLOWER1 (FvTFL1) functions as a key floral repressor that causes short-day (SD) requirement of flowering and seasonal flowering habit in the SD strawberry. In contrast, perpetual flowering F. vesca accessions lacking functional FvTFL1 show FLOWERING LOCUS T (FvFT1)-dependent early flowering specifically under long-days (LD). We show here that the end-of-day far-red (FR) and blue (B) light activate the expression of FvFT1 and the F. vesca homolog of SUPPRESSOR OF THE OVEREXPRESSION OF CONSTANS (FvSOC1) in both SD and LD strawberries, whereas low expression levels are detected in red (R) and SD treatments. By using transgenic lines, we demonstrate that FvFT1 advances flowering under FR and B treatments compared to R and SD treatments in the LD strawberry, and that FvSOC1 is specifically needed for the B light response. In the SD strawberry, flowering responses to these light quality treatments are reversed due to up-regulation of the floral repressor FvTFL1 in parallel with FvFT1 and FvSOC1. Our data highlights the central role of FvFT1 in the light quality dependent flower induction in the LD strawberry and demonstrates that FvTFL1 reverses not only photoperiodic requirements but also light quality effects on flower induction in the SD strawberry.

The Illuminating Engineering Institute of Japan Lag Scale to evaluate the wellbeing and work performance of office employees. They reported that compared to 2,900 K lighting, 17,000 K lighting helped to improve concentration and daytime alertness in office work. These results are consistent with the recent findings of Viola and co-workers 8). They exposed 104 white-collar workers to two lighting conditions (4,000 K and 17,000 K), each lasting 4 weeks, and used questionnaire and rating scales to assess their alertness, mood, sleep quality, performance, mental effort, headache and eye strain throughout the eight-week intervention. According to Viola and co-workers, exposure to blue-enriched white light improved subjective alertness, performance, and evening fatigue. Together these findings lead us to hy

This paper presents a literature review about energy-efficient retrofit of electric lighting and daylighting systems in buildings. The review, which covers around 160 research articles, addresses the following themes: (1) retrofitting electric lighting in buildings, (2) electric lighting energy use and saving potential and (3) lighting retrofit strategies. The retrofit strategies covered in the review are: replacement of lamp, ballast or luminaire; use of task-ambient lighting design; improvement in maintenance; reduction of maintained illuminance levels; improvement in spectral quality of light sources; improvement in occupant behavior; use of control systems; and use of daylighting systems. The review indicates that existing general knowledge about lighting retrofit is currently very limited and that there is a significant lack of information concerning the actual energy performance of lighting systems installed in the existing building stock. The resulting key directions for future research highlights issues for which a better understanding is required for the spread and development of lighting retrofit.

In this paper, an energy efficient streetlight for pedestrian roads is introduced. Energy efficiency is achieved via up-to-date light-emitting diode (LED) technology and added intelligence utilising integrated sensors and wireless control. Thermal and electrical design of the luminaire contributed to good technical functionality. The performance of the luminaire was validated with testing. The luminaire was compared with commercial lamp and LED-based street lighting technology by technical values and user acceptance. Energy savings of 19-44% through improved luminous efficacy was demonstrated without added intelligence. With smart control further power saving potential of 40-60% was shown depending on the lighting environment and pedestrian presence. User feedback of a pilot installation comparing commercial luminaires with the newly developed streetlight revealed that on average the users preferred the developed streetlight over the commercial luminaires.

The ‘hue-heat’ hypothesis states that an environment which has wavelengths predominantly toward the red end of the visual spectrum feels ‘warm’ and one with wavelengths mainly toward the blue end feels ‘cool’. In order to test the hypothesis and to study the impacts of the correlated colour temperature of a light source on thermal sensation and thermal comfort, a study was conducted in a test room illuminated with an Light Emitting Diode (LED) lighting system with an adjustable correlated colour temperature where air temperature, air velocity, and relative humidity were kept constant. The correlated colour temperature of lighting inside the test room was changed gradually while keeping the colour rendering index values greater than 90, an illuminance level of 500 lx, and chromaticity difference (Duv) values within the limits of ±0.005. Sixteen study subjects were exposed to a ‘high room temperature’ (25℃) and a ‘low room temperature’ (20℃) on different days. The subjects were adapted to low correlated colour temperature (2700 K), medium correlated colour temperature (4000 K), and high correlated colour temperature (6200 K) lighting for 10 min and subsequently completed the questionnaire about their thermal comfort and thermal sensation. The results of this survey did not provide support for the hue-heat hypothesis and indicated that people felt thermally more comfortable in an indoor workplace at the correlated colour temperature of 4000 K than at the correlated colour temperature of 2700 K or 6200 K.