The nZEBexpo, the largest event in Romania dedicated to energy-efficient buildings, took place at Romexpo.

Architects from Studio ae were present and answered visitors' questions about building better over three days.

The company's specialists shared their over 10 years of design experience, discussing the challenges and benefits of energy-efficient buildings.

The corner booth featured an experimental VR (Virtual Reality) experience of an energy-efficient house designed by Studio ae together with the extended team: Creative Engineering & Renso.

The NZEB House: How can this standard be achieved?

The European Directive DIRECTIVE 2010/31/EU on the energy efficiency of buildings was implemented in Romania by Law 372 of 2005, which was then completed in 2016 by Law 156. Recently, in February 2023, the methodology for applying these measures was published through standard MC001/2022. Thus, the obligation of energy efficiency has been defined and is part of the process for obtaining a building permit for an NZEB house.

Therefore, new urban planning certificates will require designing and constructing a building according to this standard. The "Study on the feasibility from a technical, economic, and environmental point of view of using high-efficiency alternative systems" is the documentation that demonstrates compliance with the NZEB standard.

What is NZEB?

Although it is called Nearly Zero Energy Building (NZEB), it does not mean that it consumes no energy or that it is not connected to utilities and the electrical grid. The NZEB standard involves a significant reduction in the use of energy from conventional sources, such as coal, oil, and gas. Gas is currently considered a transition energy source.

The goal is to reduce conventional energy consumption in buildings to near zero and to primarily use energy from local renewable sources.

There are two major directions regarding energy efficiency. On one hand, reducing energy consumption and implicitly CO2 emissions. On the other hand, producing the necessary energy for a building's operation.

What does the NZEB standard entail?

Studying and adapting to the NZEB standard means simultaneously considering multiple factors. These factors include the external environment, the building's purpose, the necessary indoor comfort temperature, and the climatic zone. Additionally, the installations, the building's envelope, and the calculation of primary energy within the building are considered.

Achieving the NZEB standard for a building represents a measurable objective. This involves designing and implementing a complete system of elements. It also requires technical specifications for materials, construction details, and types of installations.

All these decisions result in reducing the energy needed to meet people's comfort and activities.

For new buildings, such as homes, at least 30% of the energy used will come from locally produced renewable sources or within a 30 km radius of the location. The intended effect is to reduce heat losses and greenhouse gas emissions.

The aim of these regulations is to reduce greenhouse gas emissions by limiting total energy consumption. For example, for individual residential buildings in climate zone II (Bucharest), the total primary energy is limited to 127.9 kWh/m2 per year, and CO2 emissions to 16 kg/m2 per year (according to MC001).

Compliance with these parameters can be achieved by reducing the heating needs in winter and cooling needs in summer. LED lighting and other low-energy equipment can also be used.

Heating and cooling needs can be optimized the most. This can be done by improving the thermal insulation of walls, roofs, doors, and windows, and by implementing a comprehensive installation concept.

Four major factors influence achieving the NZEB standard

The building envelope comprises all elements in contact with the external environment: facades consisting of walls, floors in contact with the ground and foundations, and the closure of the top level, which can be a terrace or a roof. Proper thermal insulation of the building is essential to reduce heat loss and excessive heating in summer.

The exterior joinery consists of windows and doors, centralized in the joinery table. Windows are a system made of frames and glass that allow natural light to enter the interior. On the other hand, they are a vulnerable element if their performance regarding energy transfer (heat loss) and installation correctness is not met.

The installation systems used contribute to the building's energy balance: from interior lighting and the choice of appliances to heating and ventilation methods. All these are active systems with their own performance and energy efficiency.

Producing and using renewable energy. For example, we can use solar panels for domestic hot water preparation. We can also use photovoltaic panels to produce electricity. This electricity can be used for appliances or for charging electric cars.

Primary energy is the type of energy that has not yet undergone a transformation process. For example, electricity before being transformed into thermal energy using a radiator.

Why do we focus more on the building envelope, joinery, and heating and cooling systems?

From an energy consumption perspective, heating and cooling a building are the largest consumers. They also depend on the building envelope's performance. Therefore, it has the most significant impact.

If you have a very good heat pump but the envelope is like a thin sheet between the interior and exterior, then the building is not efficient. This means it will not function properly, and heat will transfer to the exterior during winter. If the envelope has poorly performing windows, heating the room becomes inefficient. It is like trying to heat a room while keeping the window open.

Besides the above factors, other factors need to be considered. These include sealing, avoiding thermal bridges, using passive shading and cooling systems for a building. Correct installation and execution are also necessary.

Only materials approved in Romania should be used. Consulting the architect is necessary for decision-making during execution. Only the architect has an overview of the project.

A complete integrated system on architecture-structure-installations is needed, with specific coordinated technical details and calculation briefs regarding energy efficiency, and the calculation of the global coefficient G.

Alternative energy and system usage options (renewable)

Regarding alternative energy usage options, there are several solutions. These include solar, geothermal, ground, wind, water, and biomass energy.

There are various alternative system options depending on the case and context. These include photovoltaic panels, solar panels, heat pumps, cogeneration installations, and heat recovery ventilation systems.

Conclusion

Projects have become complex, and perspectives have multiplied. A few years ago, building permits were obtained without these detailed and coordinated studies. Now, the design and permitting process requires more time and resources. Additionally, the architect's mission and expertise have become broader. (Photo: Studio AE)