As urbanization continues to accelerate, residential industrialization is emerging as a key trend, with prefabricated housing becoming a vital component of modern residential construction. In northern regions, winter heating is a critical concern. Within prefabricated homes, the design and installation of heating pipelines play a central role in the overall heating system. This article focuses on the design and implementation of common radiator heating and floor radiant heating systems, while also exploring the use of carbon-based electric heating technologies in prefabricated housing.
1. Radiator Heating in Prefabricated Residences
Design Considerations: When employing radiators for heating, it is essential to adhere to specific principles that ensure safety, cost-effectiveness, and thermal comfort. To prevent the heat medium from vaporizing, the system design must control the temperature of the water supply, keeping it below 95°C. The design must also account for the unique characteristics of prefabricated buildings and the parameters of the heating medium, aiming to balance the number of radiators across buildings sharing the same heat source to minimize system imbalance.
Since the actual radiator surface area installed usually exceeds the theoretical requirement, it is typical to size radiators in prefabricated buildings to be 10% to 30% larger than the calculated area.
Pipeline Installation: The calculation method for heat load and radiator fin count remains unchanged. Prefabricated residential buildings often feature laminated floor slabs, composed of a prefabricated slab below and a cast-in-place slab above. Because the floor’s leveling layer is only 20mm thick, heating pipes cannot be embedded within the floor surface. Moreover, installed pipelines cannot be pre-embedded in the cast-in-place slab due to the presence of reserved steel reinforcement and electrical conduits.
For high-rise buildings, heating pipes generally run from the warm shaft through beams and public space ceilings before entering individual units. Inside apartments, pipes are usually installed openly along wall corners and baseboards. Concealing pipes is only possible through subsequent interior decoration. The installation approach in multi-story buildings mirrors that of high-rises (see Figure 1).
2. Low-Temperature Floor Radiant Heating in Prefabricated Residences
Design Principles: Floor radiant heating has gained popularity in prefabricated homes due to its energy efficiency and comfortable temperature regulation. A key design strategy is to lower the indoor design temperature by 1–3°C, as the average radiant temperature greatly influences occupant comfort. Studies have shown that reducing the indoor temperature by 1°C can result in significant fuel savings.
Floor radiant heating ensures even temperature distribution, maintaining surface temperatures within a controlled range while minimizing heat loss through vertical temperature gradients. This method also preserves indoor space, increases usable floor area, and reduces energy consumption and costs. It allows for precise regulation and heat metering, simplifying energy billing.
Installation: Plastic pipes resistant to aging and high temperatures have largely replaced metal pipes in floor radiant systems. Pipe spacing is calculated according to the “Technical Regulations for Ground Radiant Heating.” The installation of water collectors and radiators before entering the residence follows standard procedures.
However, due to the limited 20mm thickness of the floor surface, geothermal coils cannot be installed directly within the slab. Therefore, low-temperature floor radiant heating is typically installed in units with raised floors, where pipes run through the floor’s loops connected to water collectors.
Traditional residential buildings widely use radiant heating with heat sources such as urban centralized heating, small gas boiler rooms, and boiler heating systems. Thus, applying these heating methods to prefabricated residences is both feasible and practical.
It is important to note that heating pipes often need to penetrate walls. Since prefabricated components are factory-produced, standardized component design and process planning are essential. Additionally, advanced drawing software helps annotate plans and determine elevations to avoid pipeline conflicts.
3. Application of Carbon-Based Electric Heating Technologies
With growing energy challenges, new heating methods must not only meet winter heating demands but also prioritize environmental sustainability. The integration of solar energy systems with electric heating as the primary energy source has attracted significant interest. Recent research worldwide has focused on carbon material-based electric heating technologies.
3.1 Conductive Concrete
Traditional concrete is widely used in construction but has poor electrical conductivity. Conductive concrete is produced by adding conductive particles, fibers, or through mud infiltration methods. This material offers high compressive strength, elasticity, low electrical resistance, and good stability, making it suitable as an auxiliary protective system.
In underfloor heating applications, conductive concrete is cost-effective, easy to construct, and improves indoor insulation. However, further research is needed to optimize its performance, circuit design, and energy savings in large spaces.
3.2 Carbon Fiber Electric Heating Technology
This innovative system uses carbon fiber strips as heating elements. These strips conduct electricity and heat at low voltage, while monitoring temperature fluctuations and energy consumption across spaces to optimize performance.
Carbon fiber offers high conductivity, low resistivity, corrosion resistance, lightweight, and a small diameter. Carbon fiber paper, produced by combining carbon fibers with other materials, is industrially scalable and shows great promise as a conductive material. This technology is well-suited for heating prefabricated residential buildings.
4. Conclusion
In summary, both traditional and prefabricated buildings rely on effective heating methods to enhance indoor comfort. When designing heating systems for prefabricated homes, it is crucial to consider their unique characteristics alongside heating efficiency and environmental impact. The integration of heating methods with building structures and design should be seamless.
Comprehensive planning, technological optimization, adherence to national policies, and cost reduction are key to improving the energy efficiency of prefabricated housing heating systems, ultimately contributing to sustainable urban development.
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