Thermal Comfort

Thermal Regulations A Brief Analysis of Home Construction

Over the past decade, the cost of building a house has increased significantly, whether it is made of brick, concrete, or wood. This phenomenon is compounded by the continuous rise in energy costs for heating homes. As a result, the vast majority of people have turned to various technical insulation solutions to improve their home's energy performance.

Highly energy-efficient houses cost 15-20% more to build compared to traditional homes. However, the investment pays off over time through reduced heating expenses, rather than offering immediate returns.

Another unpleasant phenomenon is the decrease in purchasing power. This factor severely penalizes anyone looking to build a home, as they witness rising construction costs while their incomes remain stagnant.

This is not a simple issue! On a global scale, it has become a primary objective to combat all forms of pollution and significantly reduce our environmental footprint by using healthier, cleaner, and less energy-intensive materials. By signing the Kyoto Protocol (December 1997) and subsequent ratifications, 127 countries (including Romania) committed to reducing pollutant emissions by 5.2% between 2008 and 2012 compared to 1990 levels. Since individual homes are among the largest energy consumers, the primary focus for emission reduction will be in this sector.

What does this mean for someone looking to build a new home? It means mandatory costs for better insulation.

To put it in numbers, the current average energy consumption for a home is 240 kWh/m²/year. The goal is to reduce consumption by 20% by 2012 and by 40% by 2020. New fiscal policies, subsidies, loans, and taxes have been implemented to support this objective.

Energy Performance Regulations for New Buildings and New Building Components (RT).

The 2012 Thermal Regulation (RT 2012) was replaced by the 2020 Environmental Regulation (RE 2020), which came into effect on January 1, 2022, for residential buildings and on July 1, 2022, for offices and educational institutions.

The main objectives of RE 2020 are:

1. Improving energy performance: Reducing primary energy consumption and decarbonizing the energy sources used in buildings. This includes a reduction of approximately 15-20% in primary energy consumption thresholds compared to RT 2012.
2. Reducing environmental impact: Limiting greenhouse gas emissions throughout the lifecycle of buildings, from construction to demolition. This encourages the use of eco-friendly materials and energy-efficient, low-carbon solutions.
3. Ensuring thermal comfort during summer: Introducing a new indicator, the number of discomfort degree-hours (DH), to limit discomfort during periods of intense heat and to avoid the systematic use of air conditioning.

To achieve these objectives, RE 2020 introduces stricter requirements regarding thermal insulation, building airtightness, and the use of renewable energy sources. Additionally, there is a strong emphasis on using materials with a low carbon footprint and on bioclimatic design to optimize the energy efficiency of buildings.

In conclusion, RE 2020 represents a significant step towards sustainable construction, aiming to reduce energy consumption and CO₂ emissions in the construction sector in France.

In the context of updated thermal regulations and alignment with European standards, Romania has implemented new measures to improve the energy performance of buildings.

Methodology for Calculating Building Energy Performance (Mc 001-2022) In February 2023, the "Methodology for Calculating Building Energy Performance, code Mc 001-2022" came into force, setting minimum energy performance requirements for new and existing buildings. It includes criteria for nearly zero-energy buildings (nZEB) and promotes the use of renewable energy sources.

Nearly Zero-Energy Buildings (nZEB) According to the new regulations, all new buildings must be designed and constructed to meet the nZEB standard, meaning they have very low energy consumption, with most of their energy needs covered by renewable sources. This requirement is mandatory for all new buildings in Romania.

European Objectives for Building Energy Efficiency At the European level, the goal is for all new public buildings to meet the ZEB (Zero Energy Building) standard by 2028, and for all types of new buildings to comply with this standard by 2030. For existing buildings, the deadline for deep renovation to the ZEB standard is 2050.

These regulations reflect Romania's commitment to reducing energy consumption and CO₂ emissions in the construction sector, aligning with European policies on sustainability and environmental protection.

Updated Rules for Constructing Energy-Efficient Buildings

To meet modern energy performance standards and align with European regulations, new guidelines have been established for constructing energy-efficient buildings. These rules aim to minimize energy consumption, reduce greenhouse gas emissions, and promote sustainable construction practices.

1. Compact Building Design: Buildings should have a compact shape, minimizing the surface area of walls and roofs that can contribute to energy loss. The closer the building's shape is to a cube, the more efficient it will be in conserving energy.
2. Maximizing Usable Living Space: The ratio of usable living space to the total constructed area should be maximized. Efficient space planning reduces unnecessary energy consumption per square meter, improving the building’s overall energy performance.
3. Thermal Bridge Minimization: Thermal bridges, which occur at junctions like wall-floor or window-wall connections, should be carefully addressed. Using proper insulation techniques and materials helps prevent energy loss in these vulnerable areas.
4. High Airtightness Levels: Preventing air leakage is crucial for maintaining energy efficiency. Continuous vapor barriers and high-quality sealing materials should be used to minimize air infiltration and exfiltration.
5. Passive Solar Heating: Optimize natural heat gain by orienting the building towards the south and using large windows in that direction. Double-glazed windows are recommended for southern exposures, while triple-glazed windows should be used on the north and east sides to enhance insulation.
6. Optimized Ventilation Systems: Implementing ventilation systems with heat recovery (HRV) ensures a constant supply of fresh air while minimizing the loss of heated indoor air. This approach maintains indoor air quality without compromising energy efficiency.
7. Efficient Hot Water Production: Since hot water production is a major energy consumer after space heating, using energy-efficient systems, such as solar water heaters or heat pump water heaters, is essential to reduce overall energy consumption.
8. Automated Anti-Freeze Protection: Heating systems should include automated anti-freeze features to maintain a minimum indoor temperature of 14°C, even when the building is unoccupied. This prevents damage from freezing and ensures the longevity of the structure.
9. Summer Comfort: To prevent overheating during summer, buildings should incorporate natural shading, thermal mass to absorb heat, and effective insulation. The goal is to maintain comfortable indoor temperatures without relying heavily on air conditioning.
10. Integration of Renewable Energy Sources: At least 30% of the building's total energy consumption should be covered by renewable energy sources, such as solar panels, geothermal systems, or wind energy, in compliance with the nZEB (Nearly Zero-Energy Building) standard.
11. Use of Low Carbon Footprint Materials: Select construction materials with a low environmental impact to reduce the building's carbon footprint throughout its lifecycle, from construction to demolition.
12. Compliance with nZEB Standards: All new buildings must meet the Nearly Zero-Energy Building (nZEB) standards, ensuring very low energy consumption levels with the majority of energy needs covered by renewable sources.

By adhering to these updated rules, buildings will not only meet current legal requirements but also contribute to long-term energy savings, environmental protection, and enhanced occupant comfort.

Thermal Comfort

What does it mean to feel thermally comfortable? "Neither too cold nor too hot, and free from unpleasant drafts."

The human body maintains a temperature close to 37°C through the caloric intake from food and a set of complex biological mechanisms. There is a constant exchange of heat between the human body and the surrounding environment.

To achieve thermal comfort in your home, the materials from which it is built must have the following properties:

1. Insulation: Reducing the amount of heat that passes through walls to minimize energy consumption.
• Characteristic measurement: Thermal resistance (Rt) in m²K/W and Thermal transmittance (U) in W/m²K.
2. Thermal Mass (Accumulation): The ability of materials to store and later release heat during winter and coolness during summer (for a given volume), effectively regulating indoor temperature variations.
• Characteristic measurement: Surface thermal capacity (Cts), also known as thermal inertia, measured in Wh/m²K.
3. Attenuation: The wall’s ability to dampen external temperature fluctuations throughout the day.
4. Phase Shift (Defazage): External temperature variations form a wave. The phase shift represents the time it takes for this wave to pass through the wall of the house.
• Characteristic measurement: Attenuation and transfer time (Tt), which are interrelated metrics.

How is the heating requirement calculated?

The first step is calculating the heating requirement based on the Uc coefficient value.

The Uc coefficient (expressed in W/m²·K) represents the average heat loss coefficient of the building and is composed of:

• Heat losses to the exterior (walls, floors, roofs, windows, doors);
• Losses from junction areas (thermal bridges at floors, partition walls, etc.);
• Indoor comfort temperature (expressed in °C), with 19°C considered standard for residential buildings.

Steps to calculate the Uc coefficient for a building:

1. Break down the building into exterior elements (walls, floor, ceiling, etc.).
2. Detail each exterior element, considering every material used and its thickness. (Example: a wall with 20 cm of fiberglass insulation, a 12 mm OSB board, etc.)
3. Calculate the thermal resistance of each material in the wall. Each material has its own insulating properties, defined by its thermal conductivity λ (lambda). The thermal resistance of each material is calculated as follows:

Where:

• R = thermal resistance of the material (m²·K/W)
• e = thickness of the material (m)
• λ = thermal conductivity (W/m·K)

1. Calculate the total thermal resistance of the wall, which is the sum of the material resistances (R), adding the surface thermal resistance (Rs).
2. Determine the U-value for each building element:

Where R_total is the total thermal resistance of the wall.

Calculations for determining thermal comfort

For a more detailed analysis of different types of exterior walls and to simplify their thermal evaluation, we define three types of thermal comfort:

1. Winter Comfort: The building’s ability to provide occupants with a comfortable temperature during winter while using the heating system.
2. Spring-Autumn Comfort: The building’s ability to maintain a stable temperature and reduce the usage period of the heating system.
3. Summer Comfort: The building’s ability to stay cool during summer without the use of air conditioning systems.

Evaluating Thermal Performance

In the tables below, you will find the correspondence between exterior wall structures and thermal comfort values for different wall solutions manufactured by our company.

Each value has been converted into a score from 1 to 100, with the most thermally efficient wall structure receiving a score of 100.

NOTE: Calculations for the values below were performed using the following materials:

• Wood (spruce, dried to 16% ± 2%)
• Density = 480 kg/m³
• Specific heat capacity = 0.76 Wh/kg·K
• Thermal conductivity λ = 0.12 W/m·K
• Basalt mineral wool insulation (rolls)
• Density = 25 kg/m³
• Specific heat capacity = 0.26 Wh/kg·K