Master of Science / Department of Architectural Engineering and Construction Science / Fred L. Hasler / This paper discusses the potential of using LED modules as the primary light source for office buildings’ lighting systems. The LED lamps are the newest mass-produced lamps today; they have many insurmountable advantages compared to other light sources, like long lamp life, high efficacy, and low heat emission. Because of these advantages, owners and occupants of buildings can benefit greatly from the application of LED luminaires. The main focus of this paper is in 4 categories, which include the reliability of published data, occupant comfort, energy efficiency, and the life cycle costs of building lighting systems. LED light sources are compared to other primary light sources, which include fluorescent and incandescent lamps, of low ceiling office spaces from these 4 categories. The reliability of published data discussion covers color rendering index (CRI), correlated color temperatures (CCT), lamp life, and efficacy of the different type of lamps. The criteria of LED lamps are the most emphasized point of this section. The current CRI, efficacy, and lamp life evaluation systems are not suitable for LED lamps, and this paper discusses the practical value of each of these published data in office lighting system design. Some technical reports presented in this paper show that high CRI values of LED light sources do not directly link to excellent color rendition. However, LED light sources can have similar spectrum power distributions as natural light, and offer adequate visual comfort. Efficacy and lamp life are in the same situation. Even though, the published values do not necessarily reflect the real life performance of LED lamps, they often still have the longest lamp life and highest efficacy. Human comfort is the second factor discussed. Engineers and lighting designers consider illuminance level, color rendering ability, and glare of lighting systems to be deciding factors of human comfort from a lighting design perspective. However, many medical studies show that the human is much more sensitive to the correlated color of light sources. Light sources must vary output luminous flux and correlated color temperatures over time to help occupants reach optimum office task productivity and maintain health and visual comfort. LED lamps are the only light source that can practically change both the output luminous flux and correlate color temperature without heavy extra investments in equipment, which makes it the perfect candidate for this category. Energy efficiency is the third discussion point presented in this paper. Efficacy is a widely adopted term for evaluating the energy efficiency of a lamp, which describes the ratio of the output illuminance and input power. Because the output illuminance of LED lamps is decided not only by the illuminant bodies, but also many other electronic components in the lamps, some experts suggest that using efficacy to judge LED lamps is biased. This paper states the author’s position on whether efficacy can adequately describe the efficiency of LED lamps. Costs are also an inevitable point of this paper. LED lamps have the reputation of being the most expensive type of light source, but marketing data shows that the price of LEDs has been dropping dramatically recently. Moreover, Haitz’s law predicts that the price of LEDs will drop even more in the future. In this paper, the lifecycle costs of a light system have also been addressed across different types of light sources. Some crucial drawbacks of LED lamps, such as narrow photometric distribution and thermal damage control, are also addressed in this paper. Scientists and engineers still have not found the perfect solution to these drawbacks, but they are not significant enough to jeopardize the application of LED lamps in most architectural lighting design cases. According to the finding of this paper, LED lamps are the mainstream light source of future office lighting systems. The author also gives some suggestions for using LED lamps as primary light sources in office lighting system design applications at the end of the paper.

This research focuses on understanding the relationship betweenlight art and architectural lighting design and determining towhat extent can aspects of light art be used when designingfunctional lighting for architecture.The first part of this paper looks into the historical applicationof light as a material. Light has been an important element inart even prior to the introduction of artificial light sources, butthe exploration of light as an independent material throughinstallation art only developed in the last century. Similarly inarchitecture, the impact of light on creating and shaping spaceshas been recognized since ancient times, yet it was much longerbefore the development of lighting design as an autonomousdiscipline.In recent years there is an increased need for creative expressionfrom lighting designers who are pushing the boundaries ofcommunication through light. In order to understand the extentto which successful innovative lighting schemes can drawinspiration from artwork, this research further analyses keyvisual and emotional properties of light art, as well as potentialconstraints of functional spaces. Distinction of roles of the artistand designer as well as the conditions in which they work withthe medium of light pose a challenge in relating these twodisciplines.Findings from first two parts of this research are further used toanalyse an example of an architectural lighting project, to drawconclusions about light art’s applicability to functional lighting.

This thesis is about the multicolored gradients seen when using certain dichroic color lters with artificial light. As of now, this phenomenon lacks a unambiguous descriptor, and “Goniochromatic Gradient” is proposed. With help of optical physics, the science of color vision and information about dichroic products, principles for the relationship between goniochromatic gradients and dichroic filters are formulated for anyone interested in exploring this visual phenomenon.

An analysis of existing showrooms showed that absence of atmosphere makes it hard for clients to imagine effects in a context, and that lack of guidance by the light makes the experience of the showroom overwhelming or static. Also, clients often prioritize luminaires' design over light effect, even in architectural lighting where design should be negligible. This thesis investigates whether it is possible by prioritizing light effect, to optimize the showroom experience and to direct clients' focus on the light, while minimizing the influence of design on the impression and eventually choice of luminaire. In order to achieve these goals, three main concepts are suggested – guiding light, contrasting atmospheres and sequence of presenting light effects first and luminaires afterwards. These enable good communication about light which is essential for clients to focus on the atmosphere created by the light, rather than price and design. Experiments were conducted in the basement of a Croatian company's office, where the exhibits were not the luminaires, but their light. Visitors' priorities before and after going through the installation changed significantly, which might mean that the light effect made an impact and influenced examinees to base their choice of luminaire more on light effect, than design. It is concluded that the used concepts contributed to putting more focus on the light itself. Instead of focusing solely on light experience or product, a balance between the two was achieved by prioritizing and showing the light effect first, and only afterwards joining it with the product, thus offering visitors a more complete experience of the luminaire.

In the last decade, major developments in mobile and sensor network technologies, as well as in more secure data management solutions allowed an accelerated expansion of the Internet of Things (IoT) in different markets, including the smart lighting technology. These technological developments, currently shaping the lighting industry, have the power to enhance the liveability of spaces and improve people’s lives. However, in this thesis it is highlighted how such technological evolution is often marked by an engineering character over a design approach. In particular, this thesis focuses on smart lighting technology applied in urban environments and how the integration of information technology into the physical realm can enhance space quality and empower citizens’ participation. The main body is divided into two sections: The first part provides an overview of the technological solutions that are currently being implemented in the lighting design field. The second part advances a schematic projection of future trends, starting from the analysis of what is being developed in other related disciplines, such as urban planning and visual arts. Both parts are literature-based. The final section features the opinion of noteworthy lighting professionals about possible real-life applications of smart lighting technology. Since this thesis has been written during the Covid-19 pandemic, the author decided to include speculations regarding how this event might influence the future of urban lighting.

Abstract This thesis explores the design and experience of adaptive lighting. In this research, adaptive lighting is understood as a wide concept referring to lighting which adapts to information about the environment and its users or to other information relevant to intended lighting behaviour. Adaptive lighting is approached as an element of architecture and urban space, which has an influence on the human environmental experience at various levels. The research can be defined as architectural design-based research as well as transdisciplinary research. This research explores design practice by analysing the design processes of three case studies through the research-by-design method. The essential design phases, design tasks and design methods are recognized and presented. In addition, the experiences of adaptive lighting are explored with the help of empirical qualitative research material, which is gained through evaluation of the case studies. The methods used in evaluation include in situ walking interviews and evaluation probes. In the case projects situated in urban environments and in a retail space, different forms of lighting adaptation, interaction and participation were studied. The design process of adaptive lighting can be theorized, based on the three case studies, as a three-phase process consisting of several subtasks. The design process is guided by several design factors. In the design process, cooperation with experts of interaction and system design is beneficial. The users’ experience of adaptive lighting environments is complex and multifaceted. The experiences emerge in each environment as context-related interpretations or manifestations of the general experiential aspects. Finally, adaptive lighting is conceptualized in the thesis as a holistic design task by formulating a framework for pragmatic-experiential and context-oriented design of adaptive lighting. This defines adaptive lighting as a design task from the perspectives of multifaceted users’ experience and pragmatic constraints of design practice. Future design processes should acknowledge the complexity of the design task. Then adaptive lighting can offer, besides energy savings, added value for illuminated environments on many levels of experience. The main significance of this study is to help both designers and clients to understand the diversity of the new design task, and to help to approach it from human-oriented perspective—from the perspective of inhabitants of the environments. / Tiivistelmä Tämä väitöskirja tutkii mukautuvan valaistuksen suunnittelua ja kokemusta. Työssä mukautuva valaistus ymmärretään laajana käsitteenä viitaten valaistukseen, joka mukautuu ympäristöstä ja sen käyttäjistä saatavaan tietoon tai johonkin muuhun valaistuksen tavoitellun toiminnan kannalta merkitykselliseen tietoon. Mukautuvaa valaistusta lähestytään arkkitehtuurin ja kaupunkitilan elementtinä, joka vaikuttaa ihmisen kokemukseen ympäristöstään usealla eri tasolla. Tutkimus on luonteeltaan arkkitehtuurin suunnittelulähtöistä tutkimusta ja poikkitieteellistä tutkimusta. Se valottaa suunnittelun praktiikkaa analysoimalla research-by-design-menetelmällä kolmen tapaustutkimuksen suunnitteluprosesseja. Olennaiset suunnitteluvaiheet, -tehtävät ja -menetelmät tunnistetaan ja esitellään. Lisäksi kokemuksia mukautuvasta valaistuksesta tarkastellaan analysoimalla empiiristä, laadullista tutkimusaineistoa, joka on syntynyt tapaustutkimuksia evaluoimalla. Evaluointimenetelminä ovat olleet puolistrukturoitu haastattelu, paikanpäällä tehtävä kävelyhaastattelu ja evaluointiluotain. Tapaustutkimusprojekteissa, jotka sijoittuivat kaupunkiympäristöihin ja liiketiloihin, tutkittiin erilaisia valaistuksen mukautumisen sekä valon kanssa vuorovaikuttamisen ja osallistumisen muotoja. Mukautuvan valaistuksen suunnitteluprosessia voidaan kolmeen tapaustutkimukseen perustuen teoretisoida kolmivaiheisena prosessina, joka sisältää useita alatehtäviä. Suunnitteluprosessia ohjaavat useat suunnittelutekijät. Monialainen yhteistyö suunnitteluprosessin aikana on hyödyllistä. Käyttäjien kokemukset ympäristöistä, jotka on valaistu mukautuvasti, ovat monimutkaisia ja moniulotteisia. Kokemukset muodostuvat kussakin ympäristössä kontekstisidonnaisina tulkintoina ja ilmentyminä yleisistä kokemuksellisista piirteistä. Mukautuvaa valaistusta määritellään ja käsitteellistetään tässä väitöskirjassa holistisena ja kontekstisidonnaisena suunnittelutehtävänä käyttäjän moniulotteisen kokemuksen ja suunnittelupraktiikan käytäntöön liittyvien rajoitusten näkökulmista. Tulevaisuuden suunnitteluprosesseissa tulisi huomioida suunnittelutehtävän moniulotteisuus. Näin mukautuva valaistus voisi tarjota energiansäästöjen ohella valaistuihin ympäristöihin lisäarvoa useilla kokemuksen tasoilla. Tämän työn päämerkityksenä on auttaa sekä suunnittelijoita että suunnittelun tilaajia ymmärtämään uuden suunnittelutehtävän monipuolisuus ja auttaa heitä lähestymään sitä ympäristön käyttäjien näkökulmasta.