Evaluation of the Buildings’ Shadowing in the Compact Housing Development – Selected Examples

S t r e s z c z e n i e W artykule zaprezentowano wyniki analizy zacienienia ścian budynków w wybranych obszarach zlokalizowanych w otoczeniu rynku w Leżajsku – niewielkim mieście województwa podkarpackiego. Podano własne wzory na obliczanie stopnia zacienienia z uwzględnieniem wysokości zabudowy, odległości między budynkami, ich usytuowania względem stron świata i pory dnia. Zacienienie budynków wiąże się z ograniczonym dostępem światła naturalnego, a tym samym wpływa na jakość środowiska mieszkaniowego. Wyniki analizy mogą być wykorzystane w praktyce, w zakresie kształtowania wnętrz urbanistycznych, w tym także mieszkaniowych, ważnych z uwagi na stały pobyt człowieka. Doświetlenie wnętrz obiektów jak i strefy zewnętrznej pozwala kształtować prozdrowotne środowisko mieszkaniowe oraz zmniejszać zapotrzebowanie na energię niezbędną na ocieplenie mieszkań w okresie mrozów i chłodów. K e y w o r d s : The lighting of the urban interiors; The length of the shadow; Compact housing development, The height position of the sun. 1/2018 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O N M E N T 37 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O N M E N T The Si les ian Univers i ty of Technology No. 1/2018 d o i : 1 0 . 2 1 3 0 7 / A C E E 2 0 1 8 0 0 4 J . K o b y l a r c z y k The proper arrangement of urban interiors serves man, fulfilling, at least partially, the criteria for a healthy and comfortable living environment. One of its elements is the proximity of nature and the possibility of its use for relaxation purposes, facilitated by the appropriate distances between the buildings creating the interior [2]. Due to the price of the land, especially in the city centres, the distances between the buildings are small, and thus the building development is compact. It is characteristic for both old town and modern buildings in the city centres. Too high intensity of the development is accompanied by the small social spaces – the neighbourhoods. Moreover, unfavourable shading of the interiors and buildings also becomes problematic. Limited light access lowers the standard of the space and reduces its activity [3]. It is difficult to maintain the elements of greenery in the shady places and to provide friendly and convenient living conditions for the modern man. A man who is increasingly anxious to pursue a healthy lifestyle and likes to be in an environment that allows rational management of the natural resources. It applies especially to the cities that have become – as the UN statistics show – the primary and leading places of residence presently and in the future. The interaction between the natural and man-made environment plays an important role in the undertaken actions as well as the conditions arising from the characteristics of the built area. They include the volume and the height of the objects, they line the shape of construction, the distances between the buildings, as well as their location to the directions of the world [4]. This paper presents its own formulas for calculating the degree of the shading of the buildings and the spaces between them, created by the neighboring objects.The importance of this factor stems from the fact that solar radiation affects practically all of the physical and biological processes on Earth and is essential to human life. In addition, the sunlight energy is obtained without the input connected to the source [5]. 2. SHADING OF THE URBAN INTERIORS One of the factors related to local climate conditions is the degree of shading of the buildings and the spaces between them. When considering the shading of the urban interiors, the ha angle of the sun should be taken into account (Fig.1). It depends on the latitude of the analysed point and the δ declination angle, which in turn relies on the angular position of the sun in regard to the surface of the equator. The declination angle can be calculated from the approximate formula [6]: where d determines the number of the days from the beginning of the year. The declination angle varies through the year. This variation is presented in Figure 2. The values of the δ declination angle are independent of the geographic position of the analysed point on the globe. The solar altitude represents the general case, valid for every point on the globe and any location of the building relative to the world. The solar altitude (ha) is: where is the latitude of the point in question (place). This latitude acquires a plus (+) sign for the northern hemisphere and a minus (-) sign for the southern hemisphere. On 23rd March and 23rd September, the declination angle is δ = 0°. On 22nd 38 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O N M E N T 1/2018 Figure 1. Determination of the height of the sun in relation to the building in question – determination of the angular parameters + = δ 365 284 360 sin 45 , 23 d (1)