Simulation based complex energy assessment of office building fenestration

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. Santrauka Pastaraisiais metais Lietuvoje ir kaimyninese šalyse daugeja administracines paskirties pastatu, kuriu dauguma išoriniu atitvaru yra skaidrios. Didesnis istiklinimo plotas lemia mažesnius energijos poreikius apšvietimui, tačiau didina šildymo ir vesinimo sistemu energijos poreikius, sukelia šilumini bei vizualini diskomforta. Neigiamai dideliu skaidriu atitvaru itakai sumažinti naudojami tamsinti ir kitu specialiu charakteristiku stiklai, tačiau tai savo ruožtu didina energijos poreiki apšvietimui. Todel, priimant sprendimus del pastato istiklinimo, svarbu prieš tai kompleksiškai išnagrineti konkretaus sprendimo itaka pastato energijos poreikiams. Straipsnyje pateikiama modeliuojant gautu rezultatu analize. Rezultatai parode, kad vesaus klimato šalyse, kurioms priklauso ir Lietuva, kondicionuojamu administraciniu pastatu fasadu, kai nenaudojamos apsaugos nuo saules priemones, energiškai efektyviausias istiklinimas yra i šiaures puse. Energiškai efektyviausias santykinis fasado istiklinimo plotas pietines, rytines ir vakarines orientacijos fasadams yra 20 %, o šiaurines ‐ 20–40 %. Tačiau tokie istiklinimo plotai neatitinka norminiu natūralaus apšvietimo reikalavimu. Reikšminiai žodžiai: administracinis pastatas, istiklinimas, šildymas, vesinimas, apšvietimas, energijos poreikiai, mode‐liavima

Educational Wind Tunnel

The paper analyzes an educational wind tunnel produced by the Department of Building Energetics (DBE) of Vilnius Gediminas Technical University. The equipment could be used for performing laboratory works and simple research. The article presents the projection of inflow and outlet velocity in the working chamber of DBE wind tunnel and carries out actual noise level measurement. The received data are compared with information on the level of noise generated by the fan considering instructions provided by the manufacturer. In order to assess the reliability of the computer program, simulation applying PHOENICS software has been conducted. The aim of modeling is to simulate a pilot model and to compare the obtained results with those of an analogous test presented in scientific articles.Article in Lithuania

Selection of the Efficient Glazing for Low Energy Office Building

Building’s energy efficiency is already significantly determined at an early design stage of an architectural-constructive part. It is important already at that stage to select in terms of energy and daylighting effective glazing. In this paper, influence of the building’s glazing characteristics on its primary energy demand is evaluated in a complex way, performing simulations of the annual energy demand sub hourly. Results show that in cool climate zone, to which Lithuania belongs, it is possible to decrease building’s microclimate and lighting systems’ energy demand to the level of low energy office building just with the selection of the efficient glazing characteristics. At the same time minimal requirements for daylighting are satisfied