1,721,004 research outputs found
Daylight-linked control systems: a new method to assess their performances
No full textAccording to a recent Navigant Research report (Market Data: Intelligent Lighting Controls, 2017) revenue from lighting control systems is supposed to grow at 14.3% compound annual growth rate between 2017 and 2026, considering all building types globally. The spread of sophisticate lighting controls is especially expected in tertiary applications and specifically in retail, office and education sectors, due, on one hand, to higher lighting energy costs and, on the other hand, to the necessity of guaranteeing high visual comfort conditions. Indeed, the use of smart lighting systems allows to reduce energy costs, since lights are turned on only when necessary, and to improve visual comfort, tailoring light characteristics to people needs.
Control strategies can be classified in three categories depending on the device operating the control. It can be a timer (regulating flux emission depending on a specific scheduling), an occupancy sensor (regulating flux emission depending on occupants’ presence/absence) or a photosensor (regulating flux emission depending on indoor daylight availability). Despite noticeable related achievable energy savings, the use of daylight-linked controls based on photosensors is rather limited if compared with the two other strategies. This is mainly due to difficulties in designing and properly installing them (since many factors affect these systems performances) and to uncertainties connected to achievable energy savings calculation procedures, reducing reliability in their convenience evaluation.
So, it is fundamental to experiment methodologies useful to evaluate daylight-linked control systems performances both during design phase -to predict installation usefulness- and during commissioning -to verify installation properness-.
Given that, a method is here presented in order to assess the capability of different daylight-linked control systems typologies in integrating daylight. This is based on the calculation of new performance parameters: Daylight Integration Adequacy (DIA), Percentage Light Deficit (LD%), Percentage Intrinsic Light Excess (ILE%) and Percentage Light Waste (LW%). Reported results are a summary of authors’ previous researches. Specifically, illuminance measurements were performed in an office of the Department of Industrial Engineering of the University of Naples. Collected data are referred to the workplane and to a ceiling-mounted luxmeter. Starting from this luxmeter detections and from the observed ratio of the workplane illuminance to the ceiling illuminance, the functioning of different control systems was simulated. Related performances were analyzed by means of the abovementioned parameters. Results were compared and factors mostly affecting control systems operating conditions were highlighted
Automated daylight-linked control systems performance with illuminance sensors for side-lit offices in the Mediterranean area
No full textDaylight-linked control systems (DLCSs) installation guarantees noticeable benefits, optimizing both energy
saving and occupants' visual comfort. These systems performances are influenced by different factors, above all
daylight availability. To deepen this issue, daylight illuminance measurements were performed at the workplane
and at the ceiling (corresponding to the position of a typical closed-loop photosensor) in a side-lit office
during summer and winter. The office was equipped with two windows: one facing South and the other facing
West. For each orientation, starting from measurements, the functioning of different closed-loop DLCSs was
modelled. Results underlined that proportional dimming systems guarantee the best performances for each
analyzed case, however they demonstrated that, for specific indoor daylight levels and task illuminances,
switching systems can be profitable as well. It was underlined that, for specific daylight conditions, integral reset
control guarantees performances comparable with those of proportional dimming. However, it was observed
that for integral reset and multi-levels stepped systems, the risk that total illuminances (daylight plus electric
light) are lower than the prescribed ones is higher than the other analyzed control strategies
Daylit offices: A comparison between measured parameters assessing light quality and users' opinions
No full textThe paper reports data referred to luminance and illuminance measurements performed in three offices located in Naples (latitude 40°51′ N, longitude 14°14′ E). Luminance maps are obtained through HDR imaging technique by means of a video-luminancemeter. Then users' opinions about comfort conditions in their workplaces are analyzed in typical days and compared with illuminances measured at the eye level and at the workplane and with some daylight performance indexes (Useful Daylight Illuminance and Daylight Glare Probability). Results demonstrate that, given a particular space, similar luminance trends can be observed when specific weather conditions occur. Moreover discomfort turns out to be referred to precise moments of the day and to particular weather conditions. A correspondence between daylight performance indexes and users' opinions is not always observed
Evaluating performance of daylight-linked building controls during preliminary design
No full textThanks to the spread of new light sources and of smart dynamic control systems, automation sector has begun toplay a fundamental role in lighting design. In this regard, daylight-linked control systems (DLCSs) represent aparticularly interesting researchfield, since they offer great opportunities both in obtaining energy savings andin improving visual comfort conditions. However, their use is not so spread, because of the difficulties in pre-dicting their functioning during the design process and in evaluating their effective energetic and economicadvantages: available technical solutions are so many that design choices can be very hard for specialists. Toovercome these obstacles, a precise assessment methodology is needed. Given these premises, the goal of thepaper is to show the effectiveness of new performance parameters (Daylight Integration Adequacy, PercentageIntrinsic Light Excess, Percentage Light Waste and Percentage Light Deficit) in order to evaluate DLCs perfor-mance and to underline which factors mostly affect their functioning
L'accesso di luce naturale negli ambienti interni. Considerazioni sulla scelta dei software
No full textL'impiego della luce naturale per illuminare gli interni degli edifici ha molteplici effetti positivi tra i quali il comfort ed il contenimento dei consumi energetici. Poiché la luce naturale è una risorsa estremamente variabile nel tempo, la sua corretta modellazione e l’individuazione
di parametri caratteristici quantitativi e qualitativi sono essenziali per comprendere quale sia la sua reale disponibilità in ambiente durante l’anno e quali siano gli scenari luminosi che essa determina. Per la complessità della valutazione dell’accesso e della distribuzione della
luce naturale, è indispensabile l’utilizzo di software specifici, ma gli applicativi disponibili per il
calcolo illuminotecnico sono numerosi e spesso può risultare complicato individuare quello più adatto alle proprie esigenze
Lighting quality for home-working spaces: a survey
No full textThe paper presents a survey to investigate the typical characteristics of the luminous environment of workstations organized in private houses and to test people’s average awareness about their choices regarding lighting conditions settings. The research has been carried out on a survey sample made up of home workers and students who were forced to work at home because of the pandemic constraints. Daylight and electric light characteristics in home working spaces are inquired: their description, control systems and overall evaluation are shown. Results are presented and discussed
New parameters to evaluate the capability of a daylight-linked control system in complementing daylight
No full textThe use of daylight-linked controls (DLCs) can be a valuable design strategy to improve lighting conditions of indoor environment and to obtain considerable energy savings. These systems continuously adjust luminaires flux emission to maintain a constant illuminance level at the workplane, accounting for daylight availability. However, depending on their setting and operating conditions, they can provide more or less light than necessary, determining light excess or deficit at the workplane. Generally, the quality of control strategies is measured through achievable energy savings, but this approach is too inaccurate, since it does not inform about the ability of the system to provide adequate lighting conditions. Given that, the paper proposes new indices to describe DLCs performances: Daylight Integration Adequacy (DIA), Percentage Light Deficit (LD%), Percentage Intrinsic Light Excess (ILE%) and Percentage Light Waste (LW%). DIA (and complementary parameters DIA− and DIA+) describes the occurrence of different control operating conditions (ideal functioning, intrinsic light excess, light deficit and light waste) during a specific period. LD%, ILE% and LW% define the quantity of wasted or lacking light. Moreover, a simple case study is presented, in order to demonstrate the simplicity in calculating these parameters and their usefulness
Lighting control systems: Factors affecting energy savings' evaluation
No full textThe use of automated lighting control systems allows to reduce lighting costs and to achieve significant energy savings. The energy performances of controls are affected by many factors, the impact of which is very difficult to account for during the design process. The goal of this paper is to describe the factors that influence the control systems' energy performances, to analyze how the currently available calculation tools take them into account and finally to propose a simple method to adjust results obtained from the simulation software
Strumenti di calcolo innovativi per la progettazione dei sistemi di controllo degli impianti di illuminazione
No full textLa progettazione dei sistemi di controllo automatizzati che gestiscono gli impianti di illuminazione basati sull'impiego di sensori che rilevano la luce naturale è piuttosto complessa e richiede un'analisi approfondita della disponibilità di luce naturale in ambiente interno. Un'analisi di questo tipo può essere effettuata solo per mezzo di tecniche di calcolo complesse quali le simulazioni dinamiche di luce naturale. Queste simulazioni non solo consentono di stimare l'apporto giornaliero di luce artificiale necessario ad integrare quello naturale ma aiutano il progettista ad individuare una serie di dati fondamentali per una corretta progettazione del sistema di controllo. Tramite i risultati ottenuti sarà possibile, infatti, individuare gli scenari luce più ricorrenti durante l'anno dovuti alla luce naturale, tenere conto dei rischi di discomfort e della necessità dell'impiego di schermi solari ed inoltre valutare l'impatto sul funzionamento del sistema che può avere il posizionamento del sensore di luce diurna
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