Introduction – Critical Details study material

1. Introduction

Bill nr.  555/2005 Z. z. states that, since January 1st, 2021, buildings must be designed with almost zero need of energy. A building with almost zero need of energy is, from the energy efficiency point of view, filed under A0 energy category for a global indicator, which is the primary energy. To achieve this building category, it is necessary to improve the building envelope from the heating and technological point of view and to look for the optimal solution that ensures the balance between the costs for progressive materials, technical equipment of the buildings and the overall decrease in energy demand. The building envelope also must create a design look taking sustainable architecture into account.  The only factor is the configurations of the building envelopes and the geometry of the facade elements, which determine the energy savings. One of the basic elements that has a direct impact on the energy efficiency is transparent construction. Whether it is windows or glass walls these constructions create 15 – 25% of the building envelope in older buildings and even 90% in modern the modern ones.  Therefore, the transparent constructions take part in creating the inner environment but also have influence on the final cost of building operation. Besides the element of the transparent construction itself, it is necessary to know the means of anchoring and connecting to the surrounding building constructions. It is mostly about the connection to the load-bearing construction but also connecting to the insulation system either in a new-built property or in a significant renovation. All these joints and connections of individual components have influence not only on the heat loss created by heat bridges, but also by heat losses created by infiltration of air into the interior. Heat losses creating by heat passing through the constructions, heat losses created by infiltration have therefore a significant impact on the lifespan of the building, system failures and mainly on the energy efficiency itself. Energy efficiency is the   amount of energy needed to fulfil all the energy needs connected with the normalization of the building usage, mainly the energy needed for heating and preparing hot water, for cooling, ventilation, and lighting. Energy efficiency of the building is determined by calculation or calculation by using the measured energy consumption and is given in numeral indicators of energy need in the building and the primary energy, which is the energy from renewable and non-renewable sources which has not gone through the process of conversion nor the process of transformation.

2. The factors having direct impact on the energy efficiency of the building itself

Below are listed the factors having direct impact on the energy efficiency of the building:

1. characteristics of the building construction, mainly the heating and technological characteristics of the building envelope and the aperture constructions, and the heat losses caused by the building construction and the way of its use,
2. the position and orientation of the building and the impact of external climate conditions on the internal environment, mostly the impact of air temperature, wind and sun rays,
3. internal environment including the project demands on the internal environment,
4. energy equipment, especially the kind, type and the performance of the heating system and system of hot water supply and their heat-isolating characteristics and efficiency, 
5. innate ventilation, especially the influence of heat losses on the internal environment,
6. embedded lightning device, especially its kind, type, age and physical state, lighting output and energy input,
7. local environment, especially the influence of the neighboring buildings, 
8. passive solar system and solar protection, especially the heat gain for the internal environment, 
9. air conditioning system, especially its kind, type, output, age, and physical state,
10. physical state of the building,
11. compatibility of the proposed materials, 
12. other factors influencing the energy consumption in the building, mainly the impact of heat gains.

3. Basic requirements for new and significantly renewed buildings

New buildings must fulfil normalized requirements on heating and technological features of constructions and buildings. Normalized requirements must be also fulfilled by the significantly renewed buildings. If it is functional, technically, and economically possible to make, all the building constructions where a significant renovation takes place must fulfill at least the minimum requirements of energy saving buildings. It is therefore necessary to describe the malfunctions and problems for the buildings which are planned to undergo a significant renovation since there is an open call for funding to support the renovation of the buildings where the main criterion is energy saving of at least 30%. The current inflation in energy sector shows that it is necessary to begin the renovation of the existing construction objects and lower their energy consumption demands. There are quite a lot of buildings in this country - schools, kindergartens, public buildings but mainly hospitals. Most of the existing buildings are long overdue their lifespan or are close to its end. It is mostly about low-quality insulation of the building, heating systems, hot water preparation, lighting, ventilation, but also measuring and regulation. These objects and their systems have a significant share on the overall energy consumption. One of the options how to renew these existing and original buildings is use the above-mentioned funding from the Renewal Fund. It is the opportunity of using resources under the law 555/2005 Z. z. to improve the condition for the building constructions but also other places of consumption. Therefore, for the building to use the funding from the Renewal Plan, it is necessary to fulfill certain requirements that need to be proved in the project documentation and project energy rating. It is mostly about reaching a certain level of saving which is ensured by renewing the building envelope by insulating and by changing transparent constructions. This is why the topic is very up-to-date and shows the possible risk that need to be analyzed and avoided directly in the project and realization of the building and building renewal. One of the basic requirements which need to be proved in the project documentation and in the project energy rating is the fulfillment of 30% energy saving for the global indicator, which is the primary energy. The strategic document “Renewal Plan „describes the complex renewal as a renewal where the improvement of heating and technical features of the building envelope are a big part of. The most efficient way to specify the requirement for the complex renovation is through the minimum requirements on the values of energy indicators which influence the heating and technical parameters of the building envelopes. The aim of the requirement is to ensure the agreement with the principle of the energy efficiency priority and make sure that a gas boiler is not installed in a building with high heat losses in the building envelope (e.g., in walls, windows, the roof).  The building must fulfill the required level of heating and technical features after the renovation – mainly the requirements for the coefficient of thermal conductivity and the requirements and the requirement to fulfill the energy criterion – measuring need for heating energy. Building constructions must fulfill the requirements for excluding the risk of mold growth on their inner surface (Criterion of hygiene) and on elimination of steam condensation in the building construction or on its inner surface. By fulfilling these criteria, the proof of fulfilling the basic hygiene and health protection is met. The requirements on building constructions and buildings take into consideration various levels of energy efficiency. Minimum requirements (maximum values), normalized (required), recommended and target recommended values of the requirements showing making the thermal and technical features of building constructions for the following levels are as follows:

• Energy saving building (minimum requirement),
• Low-energy building (required)
•  Ultra-low-energy building (recommended requirement),
• Building with almost zero need of energy (target recommended requirement).

In the revised directive about the energy efficiency of buildings (EPBD) is stated, that all new buildings and renewed buildings built withing the European Union after the year 2020 should reach almost zero need of energy. This means that all new and renewed buildings, if it is technically possible, will have to show very high energy efficiency and their energy needs will be significantly covered by renewable sources. When designing buildings with almost zero need of energy, it is necessary to eliminate all the risks arising at the sole preparation, drawing the project or during realization. The basic concept when designing buildings with zero energy consumption is, besides high-quality thermo-technical characteristics of the building envelope, a correct and efficient heating system, hot water preparation, system of lighting, ventilation with cooling and releasing these individual places of consumption.  It is mainly about the right design and the execution of the connection, links of individual technological stages such as connecting the transparent construction to the multi-layer building envelope consisting of the load-bearing construction and the contact insulation system. This system may be contact or ventilated. Regarding the tendencies of changes in climate conditions, it is ideal to start using ecological and accessible materials low carbon footprint in construction. One of these materials is also wood, which is used in CLT construction systems as load bearing constructions of the building envelope.  In the given paper, the options of connecting the links in transparent constructions in a family house built with a low carbon footprint and active elements integrated in the building envelope.

4. Individual stages of chosen technological procedures

The Basic aspects for a building to be categorized as a building with almost zero need of energy are mainly responsible and high-quality project preparation, building realization and realization of the individual technological procedures. Another part of these stages is also the important communication among professions to reach the set goals and the building envelope was as efficient as possible, of high quality with a long lifespan. Every profession which enters the preparation phase (the project preparation) must proceed responsibly and in their part, use the available innovations which have an impact on the lifespan of the embedded materials and their construction detail solution.  The same approach must by chosen also in the second part, where the building as well as the particular construction details are realized, (e.g., the detail of connecting the transparent structure to the building wall with the insulation system)  The foundation of having a successful building with almost a zero energy need is the communication among the particular professions, professional education and the knowledge of innovative technological solutions, checking the individual professions during construction. The analyzed stages influencing the outcome of the building process are:

• Preparation stage – the project part,

• Execution stage – execution of the building process itself along with the particular construction details

Both these stages influence the overall quality and the lifespan of the building envelope when considering the possibility of malfunctions and mainly considering the quality of the internal environment, which is nowadays being evaluated in the first stage, and check the in-situ after the realization of the building. It is the pasportization of the building before putting it into use.  You can find the individual stages and the technical solution compatibility analysis of the technical solution of transparent constructions with the building envelope and the insulation system ETICS (Figure 1).

Figure 1 Connection of two analyzed stages: preparation and execution.