Timber structure is a very complex system with its own specific character that causes a lot of difficulties for designers to predict its precise behaviour under loading. Timber construction behaviour under load is affected by many factors that in most cases influence timber constructions in a negative manner. Part of these influencing factors are properties of material, the other are components of the environment where the timber construction is located. This paper presents the results of experimental research where seventeen softwood (Pinus sylvestris L.) timber beams of rectangular cross section were tested in four point bending under long-term load in uncontrolled microclimate conditions (unheated building, all year round weather in the region of Latvia). Values of mechanical properties (modulus of elasticity), physical properties (density, amount of latewood, number of annual rings in 1 cm of wood) were measured at the start of the test; while monitoring of moisture content of wood, relative humidity and air temperature were performed simultaneously for the whole period of test. It has been observed that the main factors that significantly influence timber beam behaviour during period under load in natural climatic conditions are modulus of elasticity (MoE), density of wood and number of annual rings per 1 cm of wood. Amount of latewood showed an insignificant impact on timber beam behaviour under load.

The plants emit different types of volatile organic compounds (Bio VOC’s) and can improve air quality: they effectively remove organic pollutions and reduce the number of microorganisms in the air by releasing phytoncides. The lack of negative ions in the air can cause deterioration of the health of humans breathing it. At the same time, an air saturated with negative ions can improve the state of health and provide a comfortable environment. In this article, the influence of the plants (Cupressus macrocarpa) on the number of ions is proved, based on a series of experiments performed with applying high-voltage pulses (air ionizer). This work is devoted to the elaboration of the mathematical relationship between the air ions concentration and the factors influencing it. For this purpose an experimental stand was made, consisting of two equal compartments: one contained the plants while another one was used as a control without plants. It was concluded that the plants, in general, are able to stabilize the ion concentration and to reduce its fluctuations. The plants help to increase the concentration of negative ions and to decrease the concentration of positive ones.

The experimental studies were carried out in the most common cowsheds in Lithuania. The cowsheds involved in the research featured different insulation patterns and livestock keeping technologies where cows were kept tied or loose. The efficiency of ventilation system was measured in 7 cowsheds based on the variation in air temperature, air relative humidity (RH) and ammonia. The main problems of microclimate in Lithuanian cowsheds were found to be as follows: a high relative humidity resulting in water vapour condensation on the roof structures; the air temperature is regularly below the recommended minimum of -7 °C; the air temperature is regularly above the recommended maximum of 25 °C. Optimization of the microclimate in cowsheds concerned, it is recommended to adjust the ventilation intensity based on the difference of air temperatures within the barn and outdoors. During cold months of winter it is recommended to keep the air temperature in semi-insulated cowsheds by 8–11 °C higher than that outdoors, whereas in uninsulated box-type cowsheds with roof cement – higher by 5–7 °C, and in uninsulated box-type cowsheds with roof metal – higher by only 3–5 °C. During severely freezing periods of outdoor temperature, the air temperature was found not to drop below -7 °C only in insulated cowsheds. Whereas during extremely hot days when the outdoor temperature rises above 26–28 °C, the cowsheds of all types (those insulated and uninsulated) were found to be too hot for cows. Consequently, thermal insulation of a cowshed’s roof and adjustment of the ventilation intensity are not sufficient for solving the problems caused by heat stress in the cowsheds.

The productivity, health and welfare of cows are considerably influenced by the microclimate of the cowshed in which they live. The present paper deals with the spatial variation in temperature within uninsulated wooden cowshed and cowshed renovated from stanchions into cubicles. The type of the cowshed (uninsulated wooden cubicle cowshed and renovated cowshed made of concrete elements) influences spatial variation of indoor temperature. Greater spatial variation existed in renovated cowsheds, but these remained within the range of cows' temperature comfort zone.