site.btaInvesting in Highly Energy-Efficient Building Envelopes Reduces Energy Bills by Up to 60% - Expert

Temperatures in Bulgaria are rising, and so are people's cooling costs. What should one do to avoid pouring money into more comfort at home in the summer and winter? In an interview for BTA, Engineer Veneta Novakova, President of the Association for Façade Engineering, said the solution lies in long-term savings through investment in highly energy-efficient building envelopes. 

The Association for Façade Engineering is a non-governmental organization established more than seven years ago. It is a joint initiative of a group of professionals from leading companies in the field of façade engineering, ambitious to demonstrate the importance and enforce the necessity of a façade engineering project as part of the modern investment process.

Novakova explained that highly energy-efficient envelopes result in energy cost savings of up to 60%, reduce the carbon footprint, and the design and right choice of materials would not make the initial investment significantly more expensive. The goal of a high-performance green building is to live at least 60 years, and with good maintenance and renovation, the life of buildings with an efficient envelope could also be extended, the expert said.

Breathable facades

The basic construction of buildings in Bulgaria is reinforced concrete and brickwork. On top of this solid part of the building, ventilated facades of different materials are already being laid in the country: ceramics, stone, HPL type tiles, composite materials in a variety of colours and characteristics, the expert told BTA. The new and modern glass curtain walling with energy-efficient arrays is also becoming more and more popular.

"It is important to start choosing building materials with a really low carbon footprint, wooden structures are also topical now, but in Bulgaria, we still do not have a conversation about the return of wood even as a structural element," Novakova. She recalled that throughout the life cycle of buildings, 28% of carbon emissions are attributable to them, and 11% of these are due to materials and construction. Buildings are also responsible for 40% of energy consumption.

There is currently a lot of talk in both Europe and America about life cycle assessment and its carbon footprint. In Bulgaria, this conversation is still only on a terminological level, Novakova noted. She pointed out that the building envelope plays a crucial role in its energy efficiency, controlling heat flow, preventing heat and cold loss. It minimises energy losses and ensures maximum access of natural light, the expert explained.

"We believe that the key role in the construction of zero-energy buildings and buildings that increase the comfort of the occupants, preserving their health, is the design of their envelope and from the conceptual phase, with clear criteria that we can then evaluate and predict whether the building we are designing and which we want to build, fulfills all the characteristics that we have set at the beginning," said the expert.

Green European targets

The EU's targets include reducing greenhouse gas emissions by 55% by 2030 and moving towards zero-energy buildings. Several directives - on the energy performance of buildings, on energy efficiency, as well as the Recovery and Resilience Facility, the Horizon Europe programme, the European Green Pact and the European Building Stock Observatories - are driving the targets. Bulgaria has successfully transposed all these policies and created on their basis the National Long-term Strategy for Supporting the Renovation of the Building Stock, the Energy Efficiency Act, the National Plan for Buildings with Near-Zero Energy Consumption, Novakova told BTA. She recalled that the directive on energy performance of buildings has been revised several times and eventually all new public buildings must be zero-emission by 2028, but pointed out that this will not be practically possible. The same applies to residential buildings, which are scheduled to reduce average primary energy consumption between 2020 and 2050. 

At the same time, Novakova pointed out that at the national level the renovation programmes financed with EU funds raise the question of whether we are actually doing a deep renovation to bring us closer to the European green goals, or we are doing masking or improving the aesthetics of the appearance of the buildings. "The answer to this question is we do not know, because we do not measure the energy they consume and we do not make a comparison with the previous consumption," the expert said. According to her, energy bills of homeowners are not a transparent enough way to monitor whether Bulgaria is meeting European targets. "If at the beginning we do not set details that ensure the necessary air and water tightness of the building and its energy efficiency, how could we meet them?" the expert asked. She pointed out that certain building materials are now being prescribed and people rely on everything being executed exactly as it should be. At the same time, however, the issue of implementation control remains problematic because municipalities and construction supervision do not have this capacity and rely mainly on investor control, the expert added.

Regulatory basis

"In the relevant Regulation 7, where the criteria for heat transfer coefficients for each building are set, a year ago hasty changes were made that are not holistic, do not accurately and adequately reflect the achievements and technological capabilities of glazing systems and glazing, and do not include the expertise of NGOs, their experience and expert assessment. Now we again have an incomplete regulation, in which the heat transfer coefficients are not sufficiently lowered and this is the reason why the projects include values that are legal but insufficient for a real energy efficient renovation," Novakova argued. This is convenient for investors who are only interested in the lowest price per square meter, she added.

The Association for Façade Engineering, together with other experts, organisations and the Ministry of Regional Development and Public Works, is preparing the necessary changes to a new regulation concerning thermal insulation, waterproofing and building envelopes. Good practice guides are also being prepared - for example for the design and implementation of thermal insulation systems of buildings, for waterproofing, for building envelopes, with the aim of providing the industry with the steps to be taken to have a good building envelope, said Novakova.

Another important ordinance is on investment design, which still does not cover the building envelope in full and it remain unclear whether the envelope requires a design. The expert gave the example of the tall glass buildings along Sofia's Trarigradsko Chaussee Blvd, pointing out that a structural design is needed for this envelope, which, however, is not mandatory under the current regulations. "We do a structural design for the concrete and for the steel, but for the building envelope nobody wants that," she said. "These glasses weigh 300 to 400 kilograms; if the glass breaks and falls from  a height of 100 meters , what are the consequences for the people below?" she asked.

Financial instruments 

According to Novakova, the financial instruments offered to support energy efficient construction do not work. The main instrument should be housing loans. When the investor selling housing proves that their building has been subjected to a life cycle assessment, that they have selected materials with a low carbon footprint and that the building is energy efficient, the bank will support the project and give a few points lower interest rates for the housing loan to the buyer, the expert said. She added that this would also incentivise people to move towards buying energy-efficient buildings, because apart from low interest rates, they would also pay lower energy bills. According to her, European banks, which are represented in Bulgaria, will soon impose this model in the country because the topic of green Europe is gaining momentum.

Another problem relates to the buildings done in the 1990s. At that time, suspended facades were fashionable, made by people who thought they knew how to make them. "There is no documentation, there is no clarity about what was put in, people buy a home in a building not even knowing what the glass in their windows is, and this will come back to us like a boomerang," the expert warned, adding that this makes the responsibility of renovating residential buildings even more important.

Training

In order for energy efficient building envelopes to become widely used, it is necessary to have trained personnel. The Association organises specialised courses, but this specialty appears sporadically in secondary and higher education institutions and is not yet given the attention it deserves, the expert said. "From my experience with almost all high-rise buildings, I have come to the conclusion that when all specialties join forces, a high-performance building is indeed obtained," Novakova told BTA.