Demand-side management is widel y considered a key tool to achie ve the decarbonization on the energy sector. In this regard, providing end users with detailed infor mation about their consumption patterns is key in order to enable them to make informed decisions to reduce or adapt their energy consumption. This requires the deployment of feedback interactive technologies su ch as in-home displays, dedicated apps/web portals, or ambient interfaces. There have been extensive resea rch and numerous pilot experiences on the effect of these technologies on end-user behavior, which identi fied the importance of an appropriate device design to achieve the desired demand response. However, a clear framework to design these feedback technologies in order to ensure the desired behavioral change d oes not exist. In order to fill this gap, this paper presents an exhaustive re view of existing research on feedback, focusing especially on interactive devices. This review has resulted in the identification of ten key parameters that should be taken into account by de vice designers, including the type and form of the information provided (medium, units, disaggregation level, comparisons, goal setting ), design of the interface and devices themselves, the possible inclusion of penalties and rewards, an d privacy concerns. Recommendations to implement them in such a way that end-user interaction and resp onse is maximized are provided. These recommendations would jointly make in-home displays more effect ive in creating the desired household behavioral change to maximize ene rgy conservation. Moreover, cr itical areas where further research is necessary before a sound recomme ndation can be made are identif ied. Keywords : energy efficiency, demand resp onse, eco-feedback , in-home dis play, end-user behavior A version of this manuscript has been accepted for publication in a journal. The corre sponding citation is: Carmen Valor, Carmen Escudero, Victoria Labajo, Rafael Cossent. “Effective design of domestic energy efficiency displays: A proposed architecture based on empirical evidence”. Renewable and Sustainable Energy Reviews 114 (2019). https://doi.org/10.101 6/j.rser.2019.109301 1 Corresponding author: Tel .: +34915422800 Ext.: 22291; Email: cvalor@comillas.edu 2 1. Introduction Achieving the emissions goals set in the Paris Agreement demand s a societal effort. Households’ energy consumption is one of the targets of governm ental policies, as energy consumption in the use phase causes the largest environmental i mpacts [1]. Households are encouraged, inter alia, to reduce energy consumption by achievi ng efficiency gains or reducing environmental impact [2], by conservation [3, 4], or by load-sh ifting [5] to times where energy sources are cleaner. Demand-Side Management (DSM), which compri ses both demand response (DR) and energy conserva tion, is a widely used term to describe programs developed to influence the energy usage patterns of customers [6, 7]. These programs are oftentimes implemented in practice by means of eco-feedback devices that provide users with information about their household energy con sumption. Feedback can be provided by different means: indi rectly via billing or web port als, or directly, by using display devices [8]. In turn, display de vices comprise interactive devi ces such as (1) mobile apps or websites, (2) in-home displays providing graphic and textual vi sualizations [9] and (3) ambient interfaces. More complex tools not only provide feedback but al so allow users to manage their energy consumption by switching o n and off appliances or heatin g systems. These devices facilitate two-way communication between power ut ilities, energy suppliers and/or energy service companies (ESCOs), and home consumers [10 , 11]. Whereas interactive displays provide consumers with abundant and accessible informa tion so that they can learn about their energy spending habits and change them, ambient dis plays rely on “pre-attentive” processing of information [12]. Th e main difference with the in teractive displays is that ambient interfaces do not give specific information about energ y expenditures in the form of text or numbers, but simply alert the household that their elec tricity expenditure has changed or is about to change [13, 14]. The main focus of analysis in t his paper is interactive devices, and more specifically, in-home displays as most research has ex amined this type of device; yet, it also addresses the existing r esearch on ambient energy artef acts. The introduction of in-home displ ays has been boosted by a desi re to empower energy consumers, and by the development of feedback technologies as a mean to gain consumer engagement in energy conservation [10, 15, 16]. In-home display s are advocated as they provide users with real-time inf ormation about energy spending, facilitating a better understanding of how their daily practices affect energy consum ption [9]; they increase awareness of energy saving alternatives; and they provide incen tives to reduce consumption [17]. In a nutshell, they are deemed effective as they make hou seholds more aware of energy consumption and more knowledgeable about what causes this consu mption. This eventually gives users control over their energy consumption, which will u ltimately result in energy savings. Yet, past studies have found wide differences in the amount of energy savings actually achieved following feedback-related i nterventions [5, 9, 18, 19]. These differences have been attributed to different factors, such as the characteristics of the device , the characteristics of the household (notably, their motivation and th eir actual possibilities of re ducing their energy consumption) or to the context (i.e. climat ology constraints) [20-24]. The l atter two factors are difficult or 3 impossible to control; thus, the most plausible way of increasi ng energy savings in eco- feedback-based interventions is by improving the design of the device. The negative consequences of inad equate device design have been previously emphasized as a major constraint for the scope of eco-feedback potential [25, 2 6]. However, we lack a framework that allows designers to maximize the potential of in teractive devices to ensure the desired households’ behavioral cha nge. This paper aims to provi de such framework. An exhaustive review of approximately 90 studies on eco-feedbac k interventions, design of feedback devices and ambient energy artefacts obtained from Goo gle Scholar and WOS (using the keywords “eco feedback” OR “feedback AND energy” OR “feedba ck AND shift load” OR “smart meter” AND feedback OR “energy display” AND household) w as conducted, supplemented with meta-analyses on energy savings and energy co nservation. This review was complemented with ad hoc searches to find insights to complemen t those relevant aspects for which scant research was found. Consistent with the objective of the study, papers were analyze d to identify key parameters of design that may affect outcomes. Work on gamification was exclu ded from the analysis and readers are referred to a revi ew recently published in the jour nal for more information [27]. More specifically, ten parameters of design are identified and courses of action are recommended for each of them. Based on available evidence, thes e ten design parameters would jointly make in-home displays more effective in creating the desired household behavioral change to maximize energy conservation. This paper c ontributes to existing literature by providing a guide t o device designers based on so und empirical evidence. It also identifies critical areas for further research. 2. Parameters to consider for an effective design of in-home dis plays and eco- feedback devices Then design dimensions for interactive devices that are deemed key for the effectiveness of energy efficiency programs. This section describes these ten pa rameters in detail and provide a set of recommendations to enha nce energy conservation strateg ies using in-home displays. It is important to note that these dimensions are not completel y orthogonal and they may overlap with one another. Overall, these dimensions can be cons idered to compose the architectural design for interact ive devices, or, in other word s, they provide an empirically grounded framework for designers in order to maximize household s’ energy conservation. Figure 1 presents an overview of this architectural design, inc luding the proposals (P1 to P10) for each one of the aforementioned ten parameters (in some case broken down into several sub- topics). Figure 1. Architectural design of i nteractive devices for eco-f eedback 4 2.1. Medium of communication with end users Interactive devices have proven more effective in driving energ y savings than written feedback via emails or bills for three reasons: they provide real-time [ 5, 20, 28-32] or, at least, more frequent energy consumption data than billings or emails they c an be attuned to users’ profile, and they can flexibly accommodate different behavioral interven tions, as discusse d later [33]. Yet, real-time feedback per se does not consistently lead to re duced energy use [28, 34]. The number of interactions with the device can explain these differ ences in results. Even if the device provides real-time feedback, if users do not engage with it, the potential energy savings are jeopardized. Thus, interactiv e displays demand involvement from users. There is some evidence that interaction with the device predict energy saving s [9, 23, 36]. Thus, motivating users to interact with the devi ce is one of the key success fac tors of interactive displays. A particular form of interactive displays are localized display s. These devices provide immediate feedback about the ene rgy usage of a given appliance. Localized displays have not attracted much attention in the literature, although past studi es have shown their effectiveness in driving behavioral change. For instance, when consumers were given immediate feedback about washing machine energy usage via an attached control pane l, a 21% reduction in energy use was obtained [22]. Likewise, the installation of sensors fo r each home appliance, and the simultaneous monitoring of total electric power and gas consump tion, resulted in a 12% reduction in energy usage [37]. No study has compared different visualization tools (i.e. mobile apps vs. desktop apps, or in-home displays vs. localized displa ys) vis-à-vis households’ p