Indoor Climate After Energy Renovation of Family house

The model renovation of typical family houses in Slovakia can help everyone who want to indulge in modern 21st century living with a healthy indoor environment even in an older house. This project is not only a source of inspiration. In addition to proven tips and practical advice from experts, it will also provide complete instructions for the reconstruction of a family home with an emphasis on healthy living.

Keywords: energy, renovation; family house; indoor climate, energy evaluation

The results of an international study entitled Healthy Home Barometer 2017 showed that every sixth Slovak is not satisfied with their housing. Slovaks are troubled by insufficient light conditions or excessive humidity causing mold. Up to 21% of Slovak households are not economically able to heat their house or apartment to a comfortable temperature. The speed of the renovation process in Slovakia is also insufficient. According to available statistics, there are more than 950 000 family houses in Slovakia, of which only 35% have been renovated. The renovation project of typical family houses has them ambition to change this unfavorable statistic. The model renovation for healthy living is intended to inspire Slovaks how they can renovate their house in a financially optimal way. At the end of the entire process, they will receive modern and healthy housing that takes into account parameters in three fundamental categories – quality of housing, impact on the environment and operating costs.

Family House Renovation

Family houses built between 1950s and 1970s had a typical square floor plan and material composition. At present, many of them are inhabited, but they do not meet today´s strict thermal technical requirements. Exterior walls were built without thermal insulation. The interior and exterior finishing of the walls, ceilings, and floors are in unsatisfactory conditions. Single or double windows with simple glazing were used in these houses. The ceilings were made of wooden beams. In many cases, the roof system is degraded by time, especially due to weather conditions. The project documentation of these house was drawn by hand, as no drawing software was uses at that time (Predajnianska et al. 2021, 2022; Švarcová et al 2021). The original state of family house is showed in the Figure 1. Renovation of building structures is very important. However, it is not the only parameter that improves the energy efficiency of the building. A large share in the energy efficiency of building also plays building services. The new heat source in the renovated family house is a gas condensing boiler, which represents an excellent price-quality ratio. For domestic hot water preparation was used storage heat system with volume of 120 ℓ. Heating in the building is provided by radiators. Renovated family house is showed in the Figure 2.

Figure 1. Original state of family house in Šaľa. [Authors]

Figure 2. Renovated family house in Šaľa. [Authors]

Energy Evaluation

At the beginning of the project, several reconstruction variants were created for the family house. Each variant included different thicknesses of thermal insulation, or different heat sources. A detailed description of the various renovations will not be given. However, an energy evaluation was created for the various renovations which is given in Table 1 and Figure 3. The aim of the energy evaluation is to compare the energy needed for the family house in different variants and after the renovation. As a part of the energy evaluation, the building is classified into classes based on the energy need for heating, energy need for domestic hot water preparation, energy need for ventilation or forced air extraction, total needed energy, primary energy and emission CO₂. The renovations were designed in such a way that it was possible to create a passive building that corresponds to class A1 in the classification system. The most demanding renovation was designed in such a way that it was possible to create a nearly zero energy building, which corresponds to class A0 in the classification system. The criteria to specific total energy use for different types and global indicator classification of buildings are defined in Regulation No. 364/2010 (Decree No. 625; Standard STN EN 15603/NA: 2012).

Table 1. Energy evaluation of different types of renovation. [Authors]

The results of the energy evaluation are summarized also in the following graph, in which it is possible to compare the individual energy needs within the various variants of the reconstruction of a family house. The graph clearly shows the huge difference between the energy required for a family house in its original state and the energy need for a family house after any proposed renovation.

Figure 3. Energy needed based on energy evaluation. [Authors]

Indoor Climate Measurements

The model renovation for healthy living is intended to inspire Slovaks how they can renovate their house in a financially optimal way. The main criteria of the renovation project is the house that provides comfortable and healthy living which is affordable and repeatable. At the end of the entire process of the reconstruction of the family house, there is an increase on the living space to 115 m², an increase in energy savings of up to 80%, but above all a healthy living full of daylight and fresh air. Renovated family house has been occupied by a young family of four since September 2019. At the beginning of 2022, the stage of gathering experience with operation, monitoring and measuring key parameters began. These current measurements are ensured by the Department of Building Services at the Slovak University of Technology in Bratislava. With the consent of the family, measuring devices are currently installed in the family house, which record the interior temperature, CO₂ concentration and air humidity in every room. The measuring devices placed in the family house are COMET U3430. The datalogger measures and records the values in its internal memory. Figure 4 shows the floor plan of the first floor, where an entrance hall, a bathroom, a kitchen a living room and a children’s playroom are located. In addition to the corridor, there is a datalogger in each room, which records the mentioned values. The ideal location of datalogger is in the middle of the room, but this is not possible in all cases. The location of the dataloggers is adapted to the location of the furniture in the interior. It was also more than necessary to take into account the fact that the house is inhabited by a young family with children and the dataloggers should not disturb the comfort of residents.

Figure 4. Measuring device’s location in first floor. [Authors]

On the second floor there is a bathroom, parent´s bedroom and children´s room. In these rooms, the comfort of the residents and the placement of furniture in the rooms were also taken into account. The location of the dataloggers is shown in Figure 5.

Figure 5. Measuring devices location in first floor. [Author]

Results of Indoor Climate Measurements

The aim of the experimental measurements is to record the temperature, humidity and CO₂ concentration in the interior of a renovated family house and evaluate them. Measurement started in February 2022 and will run for two years. The values are recorded in the internal memory of the dataloggers COMET U3430. The recording interval is once per four hours. For the ongoing evaluation of the data, the measured quantities were taken from the memory of the dataloggers in the interval from February 2, 2022 to July 28, 2022. A two-week period from March 7, 2022 to March 21, 2022 was selected for the ongoing evaluation of the measured data. Figure 6 shows the progress of air temperatures in each measured room. The indoor air temperature ranged from 19 to 30°C. The drop in temperature to a lower value corresponds to the time when the room was naturally ventilated.

Figure 6. Indoor air temperature in each measured room. [Authors]

This corresponds also to the concentration of CO₂ at the given time, which is shown in Figure 7. It is clear that the object was regularly naturally ventilated, which corresponds to a regular decrease in CO₂ concentration. The last Figure 8 shows the progress of air humidity in the interior of each measured room.

Figure 7. CO₂ concentration in each measured room. [Authors]

Figure 8. Humidity in each measured room. [Authors]

The following Table 2 summarizes the minimum, average and maximum temperature, CO₂ concentration and air humidity in each room.

Table 2. Summary average temperature, CO₂ concentration and humidity [Author]

The datalogger VR2 in the children´s playroom did not work after two days from the start of the measurement. Therefore, data on temperature, humidity and CO₂ concentration in this room are unknown. After talking with the owners of the family house, information was found that this room is used very rarely.

Conclusion

The original family house was in a desolate state and uninhabited for many years. Therefore, in such a case like this one, is not possible speak about a satisfactory indoor climate. Renovation of a family house should ensure satisfactory conditions for living in terms of indoor climate. Not only the renovation of building structures and technical equipment, but also the operation of the building has a great impact on the comfort in the building. Therefore, it is more than important that even the owners of the family home care about its quality. This is mainly connected with the ventilation of the building. In cooperation with Department of Building Services at Slovak University of Technology in Bratislava, measurements of the indoor climate of building are carried out. The interim results showed that thanks to the renovation of the building, the required indoor climate for the residents is ensured in terms of temperature, air humidity and CO₂ concentration.

You can find a square family house in almost every Slovak village. Most often in original condition. The owners are attracted by reconstruction, but they don´t know where to start. The RenovActive model renovation will help everyone who wants to indulge in modern 21st century living with healthy indoor environment even in an older house. Owners of typical square family houses, such as the one in Šaľa, can find the complete instruction on how to renovate the house and transform it into healthy and modern living.

Acknowledgment

This work has been supported by Ministry of Education, Science, Research and Sport of Slovak Republic through the grant VEGA 1/0303/2021, VEGA 1/0304/2021 a KEGA č. 005STU-4/2021.

Thanks to the Velux company which established cooperation with the Department of Building Services at Slovak University of Technology in Bratislava and made it possible to be a part of the RenovActive project.

References

Decree No. 625 of the Ministry of Construction and Regional Development of the Slovak Republic dated November 22, 2006, implementing the Law No. 555/2005 Coll. on the energy efficiency of buildings and on the amendment of some laws.

Standard STN EN 15603/NA: 2012 on Energy efficiency of Buildings. Total energy demand and definition of energy assessment. National Annex.

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