Choosing the right heating system for a home renovation significantly impacts the comfort of the occupants, as well as energy consumption and costs. Underfloor heating has gained popularity due to its multiple advantages over traditional heating systems. In this article, we will delve into a detailed analysis of underfloor heating installation, covering indicative prices, consumption levels, and the impact of a house's energy insulation on its efficiency. Additionally, we will explore a hypothetical scenario regarding the installation cost of underfloor heating with a heat pump for a 75 square meter apartment in Athens.

Advantages of Underfloor Heating

  • Uniform Heat Distribution: The operating principle of underfloor heating is simple but highly effective, based on a basic physical law: warm air rises. In underfloor heating, pipes are embedded under the floor of the room. When water is heated (in hydraulic installations) or electric current flows through these pipes, the heat produced is transmitted to the floor and then to the room's air.

This process creates a uniform and steady heat distribution throughout the space, from the floor to the ceiling, ensuring that warm air moves slowly and steadily upwards, without creating the cold zones often encountered in traditional heating systems with radiators or heaters. Unlike traditional systems, where heat is concentrated near the heat source - often making the air there particularly warm - underfloor heating ensures that heat is distributed evenly throughout the space, providing a sense of comfort without extreme temperature differences.

The effectiveness of this system is not only based on its ability to provide heat but also on how it provides it. Namely, heating from the floor means that the feet and the lower part of the body, which usually feel the cold more, are warmed first. This method of heating is more natural and efficient, as it exploits the natural movement of warm and cold air, thus offering a healthier and more comfortable living environment.

Traditional types of heating can dry out the air, causing discomfort, skin, eyes, and throat irritations, as well as other health problems. Underfloor heating, operating at lower temperatures and avoiding abrupt changes in humidity, helps maintain a more comfortable and healthy humidity level indoors.

The natural preservation of humidity through underfloor heating is also beneficial for home materials, such as wooden furniture and floors, which can be damaged by excessive dryness. Thus, underfloor heating contributes to protecting the integrity and appearance of the interior decor, ensuring a more natural and comprehensive comfort experience.

Additionally, underfloor heating positively affects the air quality within a space, which is particularly important for the health and well-being of the occupants. In traditional heating systems, the warm air released by radiators or heaters can cause the stirring of dust and allergens, while the dryness caused by high temperatures can be harmful to the respiratory systems.

Energy Efficiency: Operating efficiently at relatively low temperatures reduces energy consumption and operational costs, making it a more sustainable choice compared to conventional heating systems. Aesthetics: The components of the system are under the floor, offering a clean and unobstructed appearance of the space, without the need for visible heaters or pipes.

Disadvantages

  • Installation Cost: Initially, underfloor heating can be more expensive to install than other systems, especially in renovation projects where the floor structure may need significant modification.
  • Response Time: The system takes longer to warm a space, as the heat needs to permeate the floor before it can effectively increase the room's temperature.
  • Installation Complexity: Installing an underfloor heating system can be time-consuming. This process may involve removing the existing floor, placing the pipes, covering with thermal concrete, and restoring the floor surface. This requires significant time and attention to detail.
  • Response Time: The system needs more time to warm a space, as the heat must permeate the floor before it can effectively raise the room's temperature. The underfloor heating operates based on the principle of thermal conductivity and heat accumulation. The floor, acting as a large heater, retains heat and then releases it gradually into the space. This process takes time, not only for the initial heating of the floor but also for the uniform distribution of heat in the space. The natural property of materials to accumulate and then release heat is crucial for the system's efficiency but also determines the response time needed to achieve the desired temperature.

Mechanical Study for Underfloor Heating with a Heat Pump: The Heart of the Project

The mechanical study must focus on specific parameters concerning efficiency, cost, and the economic viability of the investment. Choosing a heat pump as the heating source offers significant benefits but requires special attention in design and execution.

Thermal Performance and Sizing The heat pump must be correctly sized. This means that a detailed analysis of thermal losses through the frames, walls, roof, and floor is necessary. The performance of the heat pump, especially the coefficient of performance (COP), is crucial for the system's energy efficiency.

Thermal Conductivity and Resistance Every material in the building, from the frames to the walls and the roof, has a specific thermal conductivity (k), which indicates its ability to transfer heat. Materials with high conductivity, such as metal, allow heat to escape more easily, while insulating materials with low conductivity, such as insulating foams, limit heat escape.

The thermal resistance (R), on the other hand, expresses a material's resistance to the passage of heat and depends on the material's thickness (d) and thermal conductivity (R=d/k). Higher R values mean better insulation and fewer thermal losses.

Calculation of Thermal Losses The calculation of thermal losses (Q) in a building is made by applying the equation: Q=ΔT⋅A​/R, where ΔT is the temperature difference between the interior and exterior environments, A is the surface area of the element (e.g., wall, frame) and R is the thermal resistance.

Let's take a real example with values for the frames. Suppose we have a house with a window area of 2 square meters (A = 2 m^2) and the average temperature difference between the interior and exterior during the winter months is 20°C (ΔT = 20°C). The frames are double with a thermal resistance of R = 0.5 m^2K/W, characteristic of traditional double frames without special thermal insulation treatment. The thermal losses (Q) are calculated as follows:

Q = (ΔT * A) / R = (20°C * 2 m^2) / 0.5 m^2K/W = 80W

This means that this particular window loses 80 Watts of thermal energy due to the temperature difference between the interior and exterior environments.

If we replace the example with high-energy-efficiency frames that have a thermal resistance of R = 1 m^2K/W, then the thermal losses are significantly reduced:

Q = (ΔT * A) / R = (20°C * 2 m^2) / 1 m^2K/W = 40W

Therefore, improving the thermal resistance of the frames from 0.5 to 1 m^2K/W cuts the thermal losses in half, from 80W to 40W, showing the importance of choosing frames with better thermal insulation performance to reduce energy consumption.

Continuing from the previous example, let's consider the case of a wall with an area of 10 square meters (A=10 m^2) in a building located in an area where the average temperature difference between the interior and exterior during the winter months is 20°C (ΔT=20°C). If the wall has insulation with a thermal resistance of R=2 m^2K/W, then the thermal losses (Q) can be calculated as follows:

Q = (ΔT * A) / R = (20°C * 10 m^2) / 2 m^2K/W = 100W

This means that the wall loses 100 Watts of thermal energy due to the temperature difference between the interior and exterior environments. If we compare this case with a wall that has better insulation, for example, with a thermal resistance of R=4 m^2K/W, then the thermal losses are halved:

Q = (ΔT * A) / R = (20°C * 10 m^2) / 4 m^2K/W = 50W

If we now examine the case where thermal insulation of 8 centimeters thick is applied to the wall, providing additional thermal resistance of R=1.5 m^2K/W, then the total thermal resistance of the wall increases to R=5.5 m^2K/W.

The new thermal losses for the wall are calculated as:

Q = (ΔT * A) / R = (20°C * 10 m^2) / 5.5 m^2K/W ≈ 36.36W

Thus, with the application of thermal insulation, the thermal losses of the wall are reduced from 50W (before adding the thermal insulation) to approximately 36.36W. This means that adding thermal insulation secures a savings of about 13.64W for the specific wall.

This saving indicates the importance of improving insulation to reduce thermal losses, offering significant benefits in energy efficiency and reducing heating costs in a building. The difference of 13.64W indicates a significant improvement in energy efficiency, especially when applied to the entire building. While the amount of savings may seem small at the level of one wall, in reality, when aggregated across all the exterior surfaces of a building, it can lead to a significant reduction in heating costs.

Estimated Installation Cost of Underfloor Heating for a 75 sq.m. Apartment in Athens

Installing an underfloor heating system that operates with a heat pump in such an apartment can cost from 13 to 25,000€. This cost range takes into account the following needs and factors:

Mechanical study and project supervision by a Mechanical Engineer Installation of Piping Network Purchase and Installation of Heat Pump Labor Costs of a Thermal Hydraulic Engineer Dismantling the Floor Debris Removal Refilling the Floor with Thermal Concrete Cost of Installing New Floor Cost of Floor Supply Unforeseen work

In conclusion, investing in underfloor heating with a heat pump is a smart move for renovating your home, offering comfort, efficiency, and economy. With proper planning and the choice of quality materials, the installation cost can be a wise investment that will provide benefits for many years. As Renovator, our expertise in home renovation and our specialization in the application of modern heating technologies enable us to offer solutions that combine aesthetics, efficiency, and economy.