Jarek Kurnitski

Field survey of overheating problems in Estonian apartment buildings

In Nordic countries overheating problems have not constituted a recognized problem to date. However, modern buildings, typically with larger windows, have changed this situation. New regulations based on Energy Performance of Buildings Directive (EPBD) directive require that overheating problems are controlled and recommend the use of passive cooling measures. EPBD sets that temperature simulations or other verifications are to be used at the design stage. If necessary, passive measures may be supported with active cooling systems to meet the requirements for summer thermal comfort. During this study field measurements were conducted in more than 100 Estonian apartments by recording indoor temperatures from a 3-month period; an overheating assessment and the impact of ventilation, orientation and window size on recorded overheating were studied. Our results show that overheating occurs in the modern buildings where the average room temperature was continuously about 1K higher than in the old buildings. According to the criterion of weighted excess degree hours over+27°C used in Estonian regulation to prevent overheating, no overheating occurred in old apartment buildings, but the criterion was exceeded in 13.7% of the apartments in new apartment buildings. The results showed that, without adequate passive temperature damping measures used, modern buildings were regularly overheated.

Experimental Investigation and Modeling of the Attached Plane Jet Velocity Development Characteristics in the Transition Process in a Room

Attached plane jets are widely used in room-air distribution solutions. The turbulent attached plane jet behavior in the transition process that determines the jet behavior in the fully developed region is not completely understood, especially at relative low Reynolds numbers (<6000). This study focuses on obtaining the detailed jet mean flowfield velocity data and jet growing characteristics in the transition region. A virtual origin model was set up to predict the maximum jet velocity decay, and the experiment was carried out to validate the model. In this experiment, three Reynolds numbers—1000, 2000, and 4000—were tested at different distances from 2 to 30 slot heights downstream of the jet slot. The results are significantly different from the known theory for the third and fourth jet zones definition. The experimental data show that after six slot heights downstream distance, most of the data start to fit closely the fully developed turbulent jet velocity profiles and present self-preserving characteristics earlier than in previous studies. The maximum velocity calculated by the models showed good agreement compared with the measured data at distances of 10 to 30 slot heights.

Methodological Approach to Determining the Effect of Parallel Energy Consumption on District Heating System

Abstract District heating (DH) offers the most effective way to enhance the efficiency of primary energy use, increasing the share of renewable energy in energy consumption and decreasing the amount of CO2 emissions. According to Article 9 section 1 of the Directive 2010/31/EU of the European Parliament and of the Council of 19 May 2010 on the energy performance of buildings, the Member states of the European Union are obligated to draw up National Plans for increasing the number of nearly zero-energy buildings [1]. Article 2 section 2 of the same Directive states that the energy used in nearly zero-energy buildings should be created covered to a very significant extent by energy from renewable sources, including energy from renewable sources produced on-site or nearby. Thus, the heat distributed by DH systems and produced by manufacturing devices located in close vicinity of the building also have to be taken into account in determining the energy consumption of the building and the share of renewable energy used in the nearly zero-energy buildings. With regard to the spreading of nearly zero-energy and zero-energy houses, the feasibility of on-site energy (heat and/or electricity) production and consumption in DH areas energy (i.e. parallel consumption, when the consumer, connected to DH system, consumes energy for heat production from other sources besides the DH system as well) needs to be examined. In order to do that, it is necessary to implement a versatile methodological approach based on the principles discussed in this article.

Ventilation Positive Pressure Intervention Effect on Indoor Air Quality in a School Building with Moisture Problems

This case study investigates the effects of ventilation intervention on measured and perceived indoor air quality (IAQ) in a repaired school where occupants reported IAQ problems. Occupants’ symptoms were suspected to be related to the impurities leaked indoors through the building envelope. The study’s aim was to determine whether a positive pressure of 5–7 Pa prevents the infiltration of harmful chemical and microbiological agents from structures, thus decreasing symptoms and discomfort. Ventilation intervention was conducted in a building section comprising 12 classrooms and was completed with IAQ measurements and occupants’ questionnaires. After intervention, the concentration of total volatile organic compounds (TVOC) and fine particulate matter (PM2.5) decreased, and occupants’ negative perceptions became more moderate compared to those for other parts of the building. The indoor mycobiota differed in species composition from the outdoor mycobiota, and changed remarkably with the intervention, indicating that some species may have emanated from an indoor source before the intervention.

Summer thermal comfort: compliance assessment and overheating prevention in new apartment buildings in Estonia

This study analyses which building parameters contribute the most to overheating in dwellings and which properties will make a room ‘critical’, to be chosen for compliance assessment procedure through temperature simulation, as required in Estonia for new residential buildings. Indoor temperature measurements, conducted in 18 apartments from 16 apartment buildings, show clear evidence of overheating. Compliance assessment of 25 new buildings were conducted using IDA-ICE software. The analysed sample consisted of typical multi-storeyed buildings with mainly massive concrete structures. From the simulated buildings, 68% did not meet the requirements, showing that this relatively new building code requirement was not fully established in practice. Results of the analysis indicate that the requirement in apartment buildings is achievable without cooling, if passive measures are properly applied. Recommendations are given to designers, as well as policy-makers, to improve the situation in the residential building sector.

Data for Occupancy Internal Heat Gain Calculation in Main Building Categories

Heat losses from occupant body by means of convection, radiation, vapor, and sweat are essential data for indoor climate and energy simulations. Heat losses depend on the metabolic activity and body surface area. Higher variations of body surface area of occupants are observed in day care centers, kinder gardens and schools compared to other building categories (Tables 2 and 3) and these variations need to be accounted, otherwise in these building categories heat gains, CO2 and humidity generation are overestimated. Indoor temperature, humidity level, air velocity, and clothing insulation have significant influences on dry and total heat losses from occupant body leading to typical values for summer and winter. The data presented in this article are related to the research article entitled Occupancy schedules for energy simulation in new prEN16798-1 and ISO/FDIS 17772-1 standards (Ahmed et al., 2017) [1].

Target Values for Indoor Environment in Energy-Efficient Design

This chapter summarises the factors which should be considered in the design and operation, focusing mainly on room temperature, indoor air quality, ventilation, moisture and humidity, noise and lighting. The information is mainly based on the European Standard EN 15251:2007, but as this standard does not cover all indoor environmental factors to be considered in low-energy building design also other sources are used. Many certification systems for buildings include in the evaluation criteria both energy use and the quality of the indoor environment. Thus, it is desirable to develop systems and solutions which lead to high-quality indoor environment with low energy use. The designer shall always document design criteria for the indoor environment; these criteria shall be available with the energy use data when renting or selling the building space. It is also recommended that design values for the indoor environment and indicators for the environmental comfort are included in the energy certificate and displayed with actual values for the energy use. This chapter describes also the difference between target values for dimensioning of systems and energy calculations. Different approaches for mechanically cooled buildings and buildings without mechanical cooling are introduced, and precautions are given for the latter if to be applied in low-energy buildings.

Present Energy Performance Requirements and nZEB Targets in Some Selected Countries

At the moment, there are already some official definitions of nZEBs available at least in Denmark, Estonia, and France, but most of the Member States intensively work with national definitions and plan for nZEBs. In the following, the situation in some selected countries is reported. At the end of the chapter, the issue of comparison of national requirements is discussed and comparison results of some countries based on the data of January 2013 are shown. Some harmonization in minimum energy performance requirements can be seen.

Indoor Trichoderma strains emitting peptaibols in guttation droplets

The production of peptaibols, toxic secondary metabolites of Trichoderma, in the indoor environment is not well‐documented. Here, we investigated the toxicity of peptaibols in the guttation droplets and biomass of Trichoderma strains isolated from problematic buildings.

Experimental validation of simulation and measurement-based overheating assessment approaches for residential buildings

ABSTRACT As a part of the building design process, Estonian building code requires standardized dynamic hourly simulations to verify the building’s compliance to the summer thermal comfort requirements. In this study, we analysed this overheating assessment method for free-running residential buildings, by comparing the simulation results with measured data. Simulation models with different thermal zoning levels were studied: single-zone models, multi-zone apartment models and multi-zone whole building models. We analysed and quantified the effects of modelling detail and thermal zoning on indoor temperature and overheating estimation on the basis of five apartment buildings. Based on the results, a method, using indoor temperature measurements and outdoor climate data, to assess overheating risk has been proposed, as a relatively simple and inexpensive method for pre-defining the need for dynamic simulations.