We have to get used to the idea that we don’t necessarily have to open the windows for ventilation and air purification, explains Prof. Bojan Milovanovic, head of the department at the University of Civil Engineering and Architecture in Zagreb
An interview of Raya Lecheva, 3e-news.net/ Бизнес.dir.bg, with Boyan Milovanovic we talk about the principles of nZEB almost zero-energy buildings and the possibilities for popularizing the new methods for designing and building carbon-neutral homes. If for 4000 years we have built our homes in one way, in the last 20 years we are starting to totally change our way of life and realize that we can make our homes more efficient and sustainable. What problems and challenges do we face to achieve carbon neutral housing by 2050. The most serious problems in all EU countries are related to the lack of construction personnel and materials.
The University of Civil Engineering and Architecture in Zagreb, Croatia is one of the project partners of the Horizon 2020 nZEB Roadshow together with the Center for Energy Efficiency EnEfect, Bulgaria; Chamber of Builders, Bulgaria; Hellenic Passive House Institute – Greece; Cluster Pro nZEB-Romania, Institute for Zero Energy and Passive Buildings- Italy (ZEPHIR), Pro-Academy (Poland), LNEC (Portugal), etc.
In Croatia, you have a traveling highly energy-efficient mobile home as part of the nZEb Roadshow project, how does it differ from other buildings?
It is the first demonstration mobile home under the nZEB Roadshow project and is a pilot project that demonstrates the benefits of passive and carbon neutral homes to ordinary people, as well as to engineers, architects and other professionals. The aim is to show that the system works and meets the principles of almost zero energy buildings. First of all, the house is energy independent, with mechanical ventilation, high air tightness and energy efficient doors and windows. It produces energy in two ways – from photovoltaics on the roof and from a heat pump that uses the heat from the outside air to heat or cool the entire building and actually saves a lot of energy. We tried to make it as independent as possible by mechanical ventilation with heat recovery to supply fresh air without wasting energy. We measure CO2 in the building and in the outdoor environment, we measure the levels of pollutants that would be harmful to the occupants, such as carcinogenic elements and other dust particles, in order to have maximum information about the impact of the indoor environment. We have used eco-friendly alternatives for all furniture and interior elements.
Why don’t people in Croatia, and the same in Bulgaria, build similar passive houses? What do you think are the problems?
In my opinion, people do not believe that such buildings exist and that this is possible. They are used to opening the windows to let in fresh air. If the window is closed, people do not believe that they can get fresh air. With mechanical ventilation systems this can happen. After 4000 years we are used to opening the windows to have fresh air, in the last 20-25 years we have to get used to the thought that we don’t necessarily have to open the windows to ventilate and purify the air. It is difficult to switch to this new understanding. Even the professionals have their doubts that this is possible. That’s why we piloted this mobile home to show on a smaller scale that this is possible and works. All the principles of the almost zero-energy building can be transferred to the construction of your own home. If it has good exposure to the south, efficient appliances and options for electricity production such as photovoltaics and for heating such as heat pumps, this building will not need additional energy. The house has televisions, tablets, a refrigerator, lighting, and they all work thanks to the energy that the building itself produces from the sun and air.
Will you make your own home this way?
Yes, I would like to and I think it is quite possible.
How much is such an investment worth?
For the Croatian market, the calculations are from a few years ago, which is not comparable to the market today, because the prices are many times higher. The data then showed that for a family house the investment is up to 15% higher than for a similar house that does not meet the principles of a nearly zero-energy building, but in the long term, considering the 30-50 year life of a home, it it is definitely cheaper and pays off very quickly.
Is there support for families building similar houses in Croatia for example under the Recovery and Resilience Plan or other programs?
The nZEB standard for the construction of near-zero energy buildings in Croatia is now mandatory and has no subsidies. There are subsidies and incentives for the construction of RES installations, for example photovoltaics, for the renovation of existing buildings. But at the government level, there are no subsidies for the construction of nZEB buildings. But there are incentives at the local level, for example not paying local taxes and fees if you build an nZEB building. The investment is not small, so incentives like this one related to tax relief are good and effective. This is a saving of €10-15,000 per family home on local taxes and charges. This is enough money to buy a ventilation system or windows that insulate well, but each family can decide what to buy with this saving.
What do you think, as the head of the department at the University of Construction and Architecture in Zagreb, is the problem related to personnel and the availability of professionals in the industry?
It’s a huge problem and it has to do with people not believing it’s possible. Why? Because they are not trained, they do not know, the same applies to professionals, they have been trained in universities in one way for millennia. They are trained that you need a 25 kW gas boiler in a 55 sq m apartment. They cannot switch that 1 kW is enough to heat the same room. In Croatia we train 30% of engineers and they get knowledge about nZEB. If all multi-family and single-family residential buildings are to be renovated, which is mandatory by 2050, we must have 15,000 engineers, builders, etc. It is about 2.5 million apartments and 60,000 buildings that need renovation after the earthquakes of recent years. We need so many specialists who do not have the necessary knowledge, qualification, experience.
Why, what are the causes and what are the solutions?
The system is not very flexible. It doesn’t allow much change. We have been working to these standards for 20 years. The problem in Bulgaria with personnel is similar. There is funding, but there are no people, no engineers who can implement the renovation. We need 15,000 additional workers, given that the sector consists of 60,000 employees. We need at least 25-30% additional personnel in this sector to renew the building stock in the country, which is extremely large. We hire people from other countries – from Nepal, Ukraine, all over Eastern Europe, from Egypt, it’s crazy. A complete change in the education system is needed.
We have to meet the requirements like all EU member states, we have to achieve 100% carbon neutral buildings by 2050. We in Croatia are renovating below 1% per year, and the European targets are 3% per year, but almost all member countries move in this order of 1-1.5% per year. It is very difficult to fulfill the set goals. Many of the problems are due to the lack of construction materials to renovate the buildings. Maybe we could, but there are no materials, if we have materials, maybe we will succeed, but there are no workers. It’s a vicious circle that we have to get out of somehow. There is interest from owners, from investors, because it is profitable and makes sense. There is a huge difference between paying 20 or 120 euros per month for electricity.
Do energy cooperatives work in Croatia? And have you introduced the RES Directive in Croatia?
They are units. There is a lot of interest in building RES, but most are large photovoltaic systems. There are incentives to build small solar installations, but we are still a long way off. In Croatia, legislation still allows you to produce as much energy as you use from the grid. If you take 1 kWh per year from the grid, you have to produce that much. If you produce more, you have no alternative – there is no way to put it back on the grid and win. Therefore, it is difficult to develop this market sufficiently.
What initiatives are you planning with the mobile home in the coming months?
We organize nZEB Roadshows, engineer and builder trainings, organize open doors for children and students, participate in events and festivals across the country to show the benefits of near-zero energy buildings. More than 1,500 people visited the mobile home in May alone.
