Mergim Gaši

• Master of Science
• PhD Student at University of Zagreb

Thermal bridges have a significant impact on the energy efficiency of buildings, but their accurate assessment remains a challenge. In this paper, a novel method for estimating the Ψ-values of thermal bridges and their contribution to the transmission heat losses (Htr,TB) is proposed to solve this problem. The proposed method involves calculating t...

This study investigates mould/fungi growth risk on two different approaches of thermal bridge mitigation. Thermally insulated balconies and thermally broken balconies in Zero Emission Building (ZEB) are reviewed. Linear thermal transmittance (ψ - value), interior surface temperature and mould/fungi growth risk for five balcony designs is performed....

Even though moisture content or relative humidity are one of the basic physical properties of building materials, excessive moisture content in building materials often leads to structural damage and aesthetic changes in the material. This paper presents the results of a study investigating the use of infrared thermography (IRT) to identify and ass...

Transmission heat losses are crucial in assessing a building's energy efficiency. These losses can be determined through numerical calculations, laboratory tests, or in-situ methods. Numerical and laboratory methods require knowledge of the element layers and their thermal properties. In-situ methods, such as the Heat Flow Meter (HFM) method or Inf...

In order to maintain the quality of construction for nearly zero energy buildings and to reduce the pressure on construction workers with the addition of the need for faster and simpler structures, the use of cavity-insulated LSF (lightweight steel frame) panels is increasing. Requirements for performance quality, quality of life, and low energy co...

Reducing heat losses through the building envelope is one of the most important aspects to be met if the targets set by the European Union are to be achieved. In order to obtain a more realistic energy demand, dynamic heat transfer simulations are used to calculate the energy consumption of buildings, since steady-state calculations do not take int...

This paper proposes an improvement of the conventional Lightweight Steel Frame (LSF) wall structure suitable for the design of high-performance modular buildings. A mobile module, named MUZA, is used as a case study building to analyse the performance of such LSF structures in terms of their thermal bridging effect on the U-value of the opaque enve...

Transmission losses through the building envelope account for a large proportion of building energy balance. One of the most important parameters for determining transmission losses is thermal transmittance. Although thermal transmittance does not take into account dynamic parameters, it is traditionally the most commonly used estimation of transmi...

Historic buildings represent our cultural heritage and identity. Due to their age and building tradition, they are extremely vulnerable to seismic excitations, as confirmed by the recent earthquake in the city of Zagreb. In addition, historic buildings are among the buildings with the worst energy performance and very low indoor comfort. In the sco...

This paper presents the results of research on the influence of perforation and slits on the water vapour diffusion of expanded polystyrene (EPS) and the influence of the size and number of perforations and slits on the thermal conductivity of EPS board. The research was conducted using numerical models (control volume methods) with varying sample...

Deep energy renovation of building stock came more into focus in the European Union due to energy efficiency related directives. Many buildings that must undergo deep energy renovation are old and may lack design/renovation documentation, or possible degradation of materials might have occurred in building elements over time. Thermal transmittance...

Energy efficiency in building sector came in focus with obligation of Nearly Zero-Energy Buildings delivery. On the other hand, building sector is in a phase of digital transformation by Building Information Modeling (BIM) implementation. BIM serves as a platform for information storage and exchange connected to a digital representation of the buil...

Osim povećanog prijenosa topline, toplinski mostovi (TM) predstavljaju mjesta najvećeg rizika kondenzacije vodene pare što može: uzrokovati degradaciju materijala, stvaranje gljivica i plijesni te štetno utjecati na ljudsko zdravlje. Zbog toga je prilikom protupotresne obnove potrebno i adekvatno izolirati vanjsku ovojnicu. Kako bi se to ostvarilo...

Ovaj rad istražuje mogućnosti i ograničenja integralne obnove, s naglaskom na arhitektonsko-građevinske mjere energetske obnove, na primjeru tipične višestambene zgrade u Zagrebu. Uz poštivanje konzervatorskih ograničenja, moguće je postići smanjenje > 60 % potrebne energije za grijanje primjenom toplinske izolacije te čak > 80 % smanjenje potrebne...

Large deployment of NZEBs started recently and will increase in the near future. The lack of competences for NZEB delivering and absence of interdisciplinary approach present risk for satisfying the European energy efficiency goals. It has become clear in recent years that better management of the information during the whole life cycle of the NZEB...

Deep energy renovation of building stock came more into focus in the European Union due to energy efficiency related directives. Many buildings that must undergo deep energy renovation are old and may lack design/renovation documentation, or possible degradation of materials might have occurred in building elements over time. Thermal transmittance...

The construction industry across Europe is facing major challenges in achieving energy efficiency targets, in particular for Near Zero Energy Building (NZEB), but they are also experiencing a digital revolution, with Building Information Modelling (BIM). The Fit-to-NZEB, Net-UBIEP (Horizon 2020) and BIMzeED (Erasmus+) projects intend to improve the...

Despite numerous national regulations, it has been shown that the traditional practice when insulating building envelope is insufficient if not enough attention is given to thermal bridges. Heat losses through thermal bridges are much higher than the heat losses through the surrounding area. Because of that, the thermal bridges are accompanied by l...

To achieve the goals set by the European Union (EU) in terms of energy savings and decrease of the greenhouse gas emissions, the member states of the EU obliged that they would increase the number of the Nearly Zero-Energy Buildings (NZEB). That increase has to be accomplished not only by building new NZEBs but also by deep energy renovations of ol...

To reduce the impact on climate change, many countries developed strategies for the building sector with a goal to reduce the energy demands and carbon emission of buildings. As most buildings that exist today, will very likely exist in foreseeable future, many buildings will need to undergo major renovations. One of the most important parameters i...

To reduce the impact on climate change, many countries developed strategies for the building sector with a goal to reduce the energy demands and carbon emission of buildings. As most buildings that exist today, will very likely exist in foreseeable future, many buildings will need to undergo major renovations. One of the most important parameters i...

With the increasing number of nearly zero-energy buildings (NZEB) due to increase of global awareness on climate change, the new concepts of design and control must be developed because of great NZEB dependency on detailing and multidisciplinary approach. This paper proposes a three-level gateway control method for NZEB project delivery by using di...

Heat losses through the building envelope is one of the key factors in the calculation of the building energy balance. If steady-state heat conduction is observed, which is commonly used to assess the heat losses in building, there is an analytical solution for one-dimensional problem. For two and three-dimensional problems, especially for the comp...

The energy performance of buildings directive requires from the European Union Member States to ensure that by 31 December 2020 all new buildings are nearly zero-energy buildings (NZEBs) and after 31 December 2018, new buildings occupied/owned by the public authorities should also have the NZEB performance. The large-scale deployment of NZEBs repre...

The goal of the condition assessment of concrete structures is to gain an insight into current condition of concrete and the existence of defects, which decrease durability and usability of the structure. Defects are quite difficult to detect using infrared thermography when concrete elements cannot be thermally excited with the Sun, together with...

The Energy Performance of Buildings Directive requires from the European Union Member States to ensure that by 31 st of December 2020 all new buildings are Nearly Zero-Energy Buildings (NZEB) and after 31 st of December 2018, new buildings occupied and owned by the public authorities should also have the NZEB performance. The large-scale deployment...

This paper proposes an alternative experimental procedure that uses infrared thermography (IRT) for measuring the surface temperature of building elements, through which it is possible to approximate the thermal transmittance or the U-value. The literature review showed that all authors used similar procedures that require semi-stationary heat tran...

By 31 December 2020, all new buildings in the European Union, and therefore in Croatia, should be Nearly Zero-Energy Buildings (NZEB). A question which arises is: are the engineers and workers in the Architecture, Engineering & Construction (AEC) industry well prepared for delivering such a solution? Information loss and lack of collaboration bring...

With unsustainable greenhouse gas emission and irrational energy consumption, building sector have big impact on environment pollution and climate change. In order to reduce the building sector impact, the majority of current buildings need to be renovated and new buildings built as Nearly Zero-Energy Buildings (NZEB). Since for building renovation...

This paper aims to show a new possibility for in situ U-value determination using Infrared Thermography (IRT) method and its comparison with heat flux method (HFM). It also gives the procedure for conducting the experiment and for the analysis of measured data. The average method and the dynamic method given in ISO 6869 were used for data analysis,...

This paper aims to show a new possibility for in situ U-value determination using Infrared Thermography (IRT) method and its comparison with heat flux method (HFM). It also gives the procedure for conducting the experiment and for the analysis of measured data. The average method and the dynamic method given in ISO 6869 were used for data analysis,...

Increasing energy performance of buildings has led to increase of energy retrofit of building envelopes. Amongst mostly used solutions are systems of ventilated facades due to a variety of reasons – better energy performance, moisture control, aesthetics, etc. Those systems use metal profiles for fastening outer facade elements, and thermal perform...

One of the most important parameters for calculating heat losses in buildings is definitely heat transfer coefficient, U, and linear thermal transmittance, Ψ. This paper proposes a method based on infrared thermography (IRT) for calculating Ψ value for existing buildings and real impact of thermal bridges. Result of measurement is a thermogram from...

One of the most important parameters for calculating the heat losses through the building's external envelope is the heat transfer coefficient (U-value) and the linear thermal transmittance (Ψ-value). This paper proposes a method based on the infrared thermography (IRT) for calculating the Ψ-value for existing buildings and the real impact of the t...

Control volume approach for numerical models of point thermal bridges using analogy with electrical circuits.

As part of a thermal assessment of the building envelope, heat losses due to penetrations or similar local effects have to be calculated and where necessary minimized, so that the thermal efficiency of the building envelope is within acceptable limits. There are two types of thermal bridges: linear and point (singular) thermal bridges. Usually they...