Simulation Based Complex Energy Assessment of Office Building Fenestration

Abstract

Abstract. The number of office buildings with highly fenestrated facades is currently increasing in Lithuania and neighboring countries. Highly fenestrated facades reduce energy consumption for lighting and simultaneously increase energy consumption for heating, cooling, air conveying and may cause thermal and visual discomfort. Pursuing to reduce negative effects of the highly glazed facade, special glasses are frequently used. However, such windows usually increase demand for lighting energy. Therefore, when making early decisions about glazing the building, it is important to have a complex evaluation of energy demand related to the specific case. The paper presents the results of analysis made using energy simulation tools. The obtained results have shown that when shading is not applied, the north is the most energy efficient orientation to glazing for an air conditioned office building in cool climate zones like Lithuania. The most energy efficient window-to-wall ratios (WWR) for the south, east and west oriented façade are 20%, whereas for the north it makes 20-40%. However, such WWR values do not satisfy standard requirements for day lighting.

Impact of façade window design on energy, daylighting and thermal comfort in nearly zero-energy houses

“…A study by Lee et al [4] examined the effect of window-to-wall ratios, orientation, Uvalue, g-value and visual transmittance to find optimal window designs for office buildings in 5 typical climate zones in Asia. Similarly, Motuziene and Juodis [5] investigated the effect of window-to-wall ratios, window orientation and glazing type on the total building energy consumption for an office building in the cool climate zone of Lithuania, while a study conducted by Ko [6], explored ways of optimising daylighting and energy savings by performing simulations to find the best combination of window area and glazing properties for office buildings in six different climates in the U.S. Due to the less predictable usage and occupancy in residential buildings, the link between energy consumption, thermal environment and daylighting is less obvious in residential buildings than in commercial buildings. Furthermore, while in office buildings most energy is used for cooling and lighting, in residential buildings there has been a historical focus on reducing the energy needed for heating.…”

Roadmap for improving roof and façade windows in nearly zero-energy houses in Europe

“…While for office buildings, there are several examples of studies paying attention to whether the window options investigated are comparable in terms of daylighting and criteria for visual or thermal comfort [19][20][21][22], such studies are few for residential buildings. Seen in the light of the tendency that large and clear southoriented windows in very well-insulated dwellings are becoming less important for reducing space heating demand and more critical for thermal comfort, we believe that such investigation is essential also in residential buildings for achieving a balanced overview of future options.…”

Determination of Optimum Window to External Wall Ratio for Offices in a Hot and Humid Climate

“…The most energy efficient window to external wall ratios for south, east, and west orientations are 20%, but for north orientation is 20%-40% [36].…”