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The European Energy Efficiency Building Directive 2002/91/CE, as well as other acts and funding programs, strongly promotes the adoption of passive strategies for buildings, in order to achieve indoor thermal comfort conditions above all in summer, so reducing or avoiding the use of air conditioning systems. In this paper, the energy performances achievable using an earth-to-air heat exchanger for an air conditioned building have been evaluated for both winter and summer. By means of dynamic building energy performance simulation codes, the energy requirements of the systems have been analysed for different Italian climates, as a function of the main boundary conditions (such as the typology of soil, tube material, tube length and depth, velocity of the air crossing the tube, ventilation airflow rates, control modes). The earth-to-air heat exchanger has shown the highest efficiency for cold climates both in winter and summer. The possible coupling of this technology with other passive strategies has been also examined. Then, a technical-economic analysis has been carried out: this technology is economically acceptable (simple payback of 5 and 9 years) only in the cases of easy and cheap moving earth works; moreover, metallic tubes are not suitable. Finally, considering in summer a not fully air-conditioned building, only provided with diurnal ventilation coupled to an earth-to-air heat exchanger plus night-time ventilation, the possible indoor thermal comfort conditions have been evaluated

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In order to evaluate the circadian effects of light, an approach based only on a\ud circadian sensitivity function makes it possible to easily obtain efficiency\ud functions and action factors. However, it does not take into account the circadian\ud human response to light stimuli, which is not linear. Non-linear models are more\ud sophisticated and accurate but they are not easy to apply. In this paper a proposal\ud for an easy way to evaluate the potential ‘circadian effects’ of light sources is\ud presented. Although the model is quite simple, results are in good agreement\ud with those obtained by means of one of the most accurate non-linear models

Light plays a crucial role in affecting the melatonin secretion process, and consequently the sleep–wake cycle. Research has demonstrated that the main characteristics of lighting affecting the so-called circadian rhythms are spectrum, light levels, spatial pattern and temporal pattern (i.e., duration of exposure, timing and previous exposure history). Considering that today people spend most of their time in indoor environments, the light dose they receive strictly depends on the characteristics of the spaces where they live: location and orientation of the building, dimensions of the windows, presence of external obstructions, geometric characteristics of the space, optical properties of walls and furniture. Understanding the interaction mechanism between light and architecture is fundamental to design non-visually comfortable spaces. The goal of the paper is to deepen this complex issue. It is divided into two parts: a brief historical excursus about the relationship between lighting practice and architecture throughout the centuries and a review of the available research works about the topic. The analysis demonstrates that despite the efforts of the research, numerous open questions still remain, and they are mostly due to the lack of a shared and clear method to evaluate the effects of lighting on circadian rhythm regulation.