When planning to build a new residential house or apartment building, one of the most important aspects is the energy efficiency of the building. From January 1, 2021, all newly constructed buildings in Lithuania must comply with the A+ energy efficiency class. This means not only high thermal insulation and energy saving indicators, but also a certain level of engineering systems and technological solutions.
In this article, we will explain exactly what the A+ class means, what its main requirements are, how much it costs, and what you need to know to ensure that your construction project complies with all applicable legislation.
What is the A+ energy efficiency class?
Class A+ is a category of nearly zero-energy buildings regulated by both national and EU legislation. Buildings in this class must be designed to consume as little energy as possible and obtain most of it from renewable sources. The main difference between the A, A+, and A++ classes lies not only in the level of thermal insulation, but also in the efficiency of engineering systems, airtightness, and the integration of renewable resources.
“Class A+ means that a building is not only well insulated, but also interacts with the environment – it passively saves energy and actively produces or uses green energy,” says Andrius Petkevičius, energy certification expert.
What is the difference between A, A+, and A++ classes?
- A class: high thermal resistance, but renewable energy is not required.
- Class A+: stricter requirements for airtightness, energy savings, and at least partial use of renewable energy sources.
- Class A++: the highest level, where energy consumption is almost zero or the building produces more energy than it consumes.
An A+ class building must not only use heat efficiently, but also have appropriately designed systems – from heat recovery ventilation equipment to alternative energy solutions.
When is A+ class mandatory and to which buildings does it apply?
A+ energy efficiency class in Lithuania is not just a recommendation – it is a mandatory requirement for all new buildings, effective from January 1, 2021. This change is part of Lithuania’s commitments to European Union directives aimed at reducing overall energy consumption and greenhouse gas emissions.
When does the requirement come into force?
According to information from the Ministry of the Environment, from 2021, when constructing any new building – whether a detached house, apartment building or public building – it will be mandatory to ensure that it meets the criteria for class A+. This means that the design stage must include solutions that meet the specified levels of thermal insulation, airtightness, and efficiency of engineering systems.
Does this apply only to new buildings?
Yes, the A+ class requirements apply only to new buildings. However, if an existing building is to be renovated or refurbished, depending on the extent of the intervention, it may be required to achieve at least class C or B, and in some cases class A. In each case, the requirements are assessed individually based on the regulations in force at the time the building permit was issued.
Class A+ is the minimum standard for new buildings only. This means that even if a small house with an area of 50 m² is being built, it is still subject to the same energy efficiency criteria as a 200 m² villa.
Basic requirements for class A
In order for a building to be classified as energy efficiency class A+, it is not enough to simply insulate the walls or roof to a high standard. This class has complex requirements that cover the thermal properties of the building envelope, airtightness, the efficiency of engineering systems, and the use of renewable energy. All these indicators must be based on calculations and proven through energy performance certification.
Thermal resistance of building envelopes
All external building envelopes – i.e., walls, roofs, floors, floors, windows, and doors – must meet strict thermal resistance (R) and heat transfer coefficient (U) requirements.
- For walls U ≤ 0.11 W/(m²·K)
- Roof U ≤ 0.09 W/(m²·K)
- Windows and doors U ≤ 0.85 W/(m²·K)
The requirements are based on standards, and failure to comply with them means that the building will not receive an A+ certificate, even if all other parameters are met.
Elimination of thermal bridges
When designing an A+ class building, it is necessary to eliminate thermal bridges – places where heat insulation may be poorer due to materials or structural solutions. These are usually window installation areas, foundation joints, and corners.
All these areas must be addressed so that there are no heat loss points that would increase overall heat consumption and reduce the building’s class.
Air tightness (Blower Door test)
One of the most important A+ criteria is the air tightness of the building. According to legislation, the air permeability coefficient (n₅₀) of an A+ class building must not exceed 0.6 1/h, which is checked by performing a so-called “Blower Door” test – the building is hermetically sealed and the air flow through leaks is measured.
This test is mandatory during certification, and negative results may be grounds for not granting the A+ class. For this reason, attention must be paid to airtightness not only during design but also during construction, especially when installing windows, floors, and sloping roof joints.
Engineering systems
In addition to thermal insulation and airtightness, the A+ class also has requirements for engineering systems. The building must be equipped with energy-efficient heating, ventilation, hot water, and electrical systems.
The seasonal efficiency coefficient (SCOP or SEER) of the equipment used must meet the minimum requirements; it is usually recommended to choose heat pumps or other high-efficiency sources.
“Many people think that thick insulation in the walls is enough. But if you install a cheap, inefficient boiler or windows with poor sealing, the A+ class will remain only theoretical,” says Eimantas Gargasas, construction consultant.
What heating and ventilation solutions are necessary for an A+ class building?
The A+ energy efficiency class requires not only well-insulated walls, but also efficiently operating engineering systems.
One of the most important elements in achieving such energy efficiency is ventilation, heating, and renewable energy solutions, which contribute significantly to the overall energy balance of the building.
Recuperative ventilation system – almost a necessity
According to the recommendations of the Ministry of the Environment and the energy efficiency assessment methodology, a recuperative system is practically inevitable if A+ class is to be achieved.
This system not only ensures fresh air in the rooms, but also recovers up to 80-90% of the heat from the exhaust air, thus reducing the need for heating.
Without mechanical ventilation with heat recovery, it is very difficult to achieve low energy consumption, especially in smaller buildings where natural ventilation causes significant heat loss.
Heating systems: efficiency is more important than type
There is no specific type of heating system required for class A+, but it is essential that it is energy efficient. The most popular solutions are:
- heat pumps (air-water, ground-water);
- gas condensing boilers (in some cases);
- combined solutions with domestic hot water production.
The seasonal performance factor of the systems used must be high enough to meet the total calculated energy demand and achieve the required building class. The higher the efficiency of the system, the lower the residual energy demand that must be covered by renewable sources.
Renewable energy – a mandatory component
According to the current methodology, A+ class buildings must use at least part of their energy from renewable sources. These may include:
- solar power plants (photovoltaic systems),
- solar collectors for hot water production,
- biofuel boilers, or other solutions using renewable resources.
According to the Ministry of the Environment, these sources must cover at least 10-15% of the building’s energy needs from renewable sources in order for the building to be classified as A+.
“Sustainability and efficiency are not goals for the future, but the norm for the present. Every A+ building must integrate advanced systems that work together to save energy.” – Rūta Zableckienė, Senior Specialist at the Construction and Spatial Planning Policy Group of the Ministry of the Environment.
How much do A+ class solutions cost and is it worth investing in them?
One of the most common questions among builders is whether it is really worth striving for an A+ energy efficiency class. Although this will be mandatory for all new buildings from 2021, these requirements have a direct impact on the construction budget. However, on closer inspection, this investment usually pays off not only economically but also legally, due to a simplified commissioning process and higher property values.
How much does construction cost on average?
According to the Ministry of the Environment, the transition from class A to A+ increases the total construction budget by an average of 8–12%. Additional costs arise due to:
- higher thermal insulation requirements (thicker layers, more expensive materials);
- the need for heat recovery ventilation systems;
- high-efficiency heating equipment (e.g., heat pumps);
- the integration of solar power or other renewable energy sources.
These investments are usually divided between building materials and engineering systems. Meanwhile, design and coordination costs do not change significantly, as A+ class design has already become the market standard.
Can a financial return be expected?
Yes, and not only from lower heating costs. An A+ class house:
- consumes up to 40% less heat energy than a B-class equivalent;
- is valued higher on the market;
- has greater opportunities to receive state support or incentives (if provided for in support programs).
In addition, many commercial banks offer better financing terms or “green loans” for buildings that meet A+ or A++ standards. This means that part of the investment can be offset by lower loan interest rates.
“Today, an A+ class house is not a matter of prestige, but a necessity. Investing in efficiency is not a choice – it is a strategic safeguard against energy crises,” says Gediminas Markevičius, an expert at the Housing Energy Efficiency Agency.
Who assesses and certifies energy classes
In order for a building to be officially recognized as A+ class, it must undergo energy performance certification. This process is regulated by a methodology approved by the Ministry of the Environment, and the assessment is carried out only by certified building energy efficiency certification experts listed in the registers of the State Energy Regulatory Council (VERT) and the Construction Inspection.
When is certification carried out?
Certification can be carried out in two stages:
- Project certification – carried out during the design stage and submitted with the building permit documents. It shows that the project meets the requirements of class A+.
- Final certification – carried out at the end of construction, before declaring the completion of construction. This certificate is the official document that must be submitted to the Registry Center when registering the building.
The final certificate must be prepared based on the actual situation, including the solutions implemented during construction, the authenticity of the thermal insulation layers, the results of the airtightness test, and other parameters.
What does the expert check?
The expert assesses the following aspects:
- the thermal resistance of the building envelope (based on drawings and actual construction);
- the efficiency of engineering systems (heating, ventilation, hot water supply);
- the airtightness of the building (if a blower door test has been performed);
- the integration of renewable energy sources (if installed).
The assessment is performed using calculation programs and methodologies approved by the Ministry of the Environment. The result is an energy performance certificate indicating the building’s class, actual energy consumption, and justification for the class.
“The certificate is like a technical passport stamp—without it, even the best-designed house remains just a declaration,” says Lina Švedienė, an assessment specialist at the Construction Inspection Authority.
Need help?
The requirements for the A+ energy efficiency class can be complex, ranging from specific thermal resistance standards to heat recovery systems and airtightness tests.
Every step in the construction process must be planned responsibly so that the building not only meets the requirements but is also properly registered, avoiding bureaucratic obstacles.
If you are unsure where to start or whether your project meets the applicable energy efficiency requirements, the stav.lt team can help you.
We provide consulting on:
- design solutions that meet A+ class requirements;
- technical construction requirements and their practical implementation;
- energy performance assessment and certification issues;
- we help prepare the documents required for the completion of construction.
Our experts work closely with architects, assessors, and government agencies, so we can ensure that your construction process runs smoothly and in compliance with all legal requirements. Contact us – we will help you achieve A+ class without stress.