Thread Content
China has been developing new types of wall materials for several decades. The promotion of energy efficiency in buildings was based on the heating energy consumption associated with standard residential designs during the 1980–1981 period; in 1986, standard JGJ26—86 established an energy-saving target of 30%. By 1995, the new standard JGJ26—95 raised this target to 50%. With the introduction of the Regulations on Energy Efficiency Management in Civil Buildings, comprehensive efforts to improve energy efficiency in domestic construction were launched. Despite development in recent years, the promotion of new wall materials and building energy efficiency still faces some challenges in practical applications. For example, the use and development of new types of wall materials produced by some companies are restricted ； Some new types of wall materials cannot enjoy various preferential treatments under the wall renovation policies ； Some energy-efficient buildings are unable to, or cannot fully, receive the refund from the special fund for wall modifications after completion and acceptance. The main reasons are the lack of scientific policy coordination, as well as outdated definitions of new wall materials that are closely related to policy implementation. At that time, the purpose of defining new types of wall materials was to prevent the destruction of arable land through brick burning and soil extraction, to protect farmland, and to encourage the use of various industrial waste residues as substitutes for clay in brick manufacturing. Therefore, the definition of new wall materials fails to reflect the functional connection with building energy efficiency and new building structure systems, exhibiting certain limitations and narrowness. Therefore, it is necessary to establish clear definitions for relevant policies and new types of wall materials in order to guide work. I. Principles and significance of defining new wall materials and building energy efficiency When new types of wall materials were first defined, building energy efficiency efforts were still in the conceptual stage, with pilot and demonstration projects being carried out. The walls of buildings are basically made up of a single type of wall material; there are few varieties, the specifications are uniform, and the technical complexity is not high. At that time, as long as designs were carried out in strict accordance with architectural design standards and construction procedures were followed, the requirements of the buildings could be basically met. With the full implementation of **building energy efficiency standards, new types of energy-efficient building structure systems have emerged in large numbers, and high-quality, new energy-efficient wall materials have come into use as a result ； Construction techniques, as well as construction machinery and equipment, are also constantly being updated. These changes create substantial opportunities for the production and use of new types of wall materials, but they also impose higher standards and requirements on their research, production, and application. Therefore, it is necessary to shift traditional management concepts, keep up with market trends, and move forward in the direction of composite materials, composite structures, composite walls, lightweight and high-strength materials, as well as new types of building structure systems. Any wall material that is suitable for constructing energy-efficient, waste-utilizing, and resource-saving buildings should be included in the scope of wall material reforms that are \"encouraged and supported.\" Otherwise, it should be listed in a separate register, with development restricted and prohibited. To make the definitions established within this framework more standardized, scientific, reasonable, and easier to apply, the following suggestions are put forward: 1. Eliminate confusion and inconsistency. At present, some substandard products that are classified as new wall materials using such terms are labeled as such and flood the market for new wall materials, thereby enjoying **preferential policies regarding wall renovations and taxes. The defective products mentioned here are divided into three categories. The first category includes products for which there are no **national standards, industry standards, or local standards; in such cases, other similar standards must be applied, and some necessary testing data and parameters are lacking (such as in the case of carbonized bricks made from industrial waste) ； Another category includes materials for which there are national standards or industry production standards, but no architectural design standards or corresponding construction guidelines (such as autoclaved lime-sand porous bricks, concrete porous bricks, etc.) ； There are also production standards, but those that explicitly prohibit certain materials from being used (such as autoclaved lime-sand bricks, etc.). The aforementioned new type of wall material cannot be used at all in the interior and exterior walls of a building’s enclosure structure, so how can it be considered new? 2. Unify technical standards. The relevant standards for new wall materials are not sufficiently scientific and reasonable in terms of their integration. For example, some products pass the tests in accordance with national or industry standards, but according to the requirements of the **Code for Design of Masonry Structures**, the masonry constructed using such products is considered unsatisfactory. The Code for Seismic Design of Buildings also sets restrictions on the use of certain qualified products. There are also some products manufactured from industrial waste residues; due to significant changes in the raw materials and their proportions, only similar standard references can be applied, yet the internal properties and quality of these products differ considerably from those standards, which is one of the reasons why the masonry fails to meet the required specifications. Comprehensive evaluation indicators for walls should serve as the basis for formulating new standards for wall materials. 3. Conducive to wall reform. Building energy efficiency standards have been in effect for many years, and practice has shown that it is difficult and uneconomical to achieve 50% or 65% energy savings relying on a single material alone. Therefore, when selecting new wall materials, it is essential to consider their overall performance – that is, to determine which materials can be used in combination with them in the most reasonable, economical, and safe manner, while ensuring the durability and stability of the masonry. This is the concept of composite walls mentioned earlier, and it is also the key to the success or failure of wall reforms. Only wall materials that can form qualified walls can be called new types of wall materials. 4. Encourage technological innovation. Some innovative new energy-saving building structure systems have, in terms of material usage, gone beyond the traditional approaches to selecting wall materials. They are essentially combinations of various building materials. If we consider the materials used for walls individually, each one has its own shortcomings; however, through scientific and rational combination and pairing, the advantages of these different materials can be combined, thereby enabling the wall to fulfill the requirements of the building as a whole. These should become the direction for the development of wall reform. II. Criteria for Identifying and Classifying New Wall Materials As is well known, walls made of wall materials can be roughly divided into several major categories, such as brick masonry structures, block masonry structures, slab masonry structures, shear wall structures, frame structures, and frame-shear structures. Structures of the same type are further divided into solid and hollow walls ； Load-bearing and non-load-bearing walls, etc. Regardless of the type of wall, it is necessary to ensure the safety, durability, and physical performance requirements of the building, while also adhering to the principles of energy conservation, waste utilization, and resource saving. Therefore, it is necessary first to determine that new wall materials must be qualified wall materials ； Secondly, it is also necessary to determine whether the new wall materials meet the comprehensive performance requirements of walls. Only materials that pass the tests for qualified walls can be considered as new types of wall materials. This fact serves as the basis for formulating policies to encourage their development; depending on the economic and technological conditions at different times, relatively mature wall (building) systems should be selected and included in lists that encourage and support their development, along with certain constraints such as requirements regarding hole ratios and bulk density. Any wall material that meets the comprehensive performance requirements specified in the catalog should be classified as a **new type of wall material whose development is encouraged and supported. III. Discussion on the application methods for defining new wall materials As mentioned earlier, the principles underlying the definition of new wall materials should ultimately be reflected in the goal of \"encouraging and supporting the construction of buildings that are energy-efficient, make use of waste materials, and conserve resources.\" The macro definition refers to the structural system of a building, corresponding to which are the building’s walls. Specifically, it refers to the enclosure structure of the building’s main body—the interior and exterior walls. Wall materials, buildings, and building structural systems form an integrated whole; none of the three can be omitted. Within the framework of **encouraging and supporting the development of building structure systems or the enclosure structures of buildings—namely the overall framework of interior and exterior walls**, various levels of government, in light of the local economic conditions and available resources, select building structure systems that are suitable for local development, introduce implementation measures and corresponding preferential policies, and improve various administrative and technical regulations. The focus of the regulatory authorities should be on establishing and managing the market. Policy and financial support should be provided for wall materials that meet the requirements set out in the catalogues for systems or wall materials whose development is encouraged and supported, so as to create a fair competitive market environment for enterprises. These enterprises should be supported and guided to carry out relevant research and production in accordance with the principles of the market economy, in order to meet market demands. Systems or walls listed in the restricted development catalog are not eligible for any preferential policies. Systems or walls listed in the prohibited development catalog must be strictly banned. Those who disregard prohibitions should be given corresponding punishment. For example, according to the existing definition standards for new types of wall materials, buildings with concrete shear wall structures, frame structures, and frame-shear wall structures are all classified as buildings using such new wall materials, and they are eligible for the preferential policy of exemption from wall modification fees. However, in accordance with the new national policy on resource conservation, it should be included in the list of sectors whose development is restricted, and shall not be eligible for preferential policies. Because concrete is composed of main raw materials such as cement, sand, and stones (limestone). Cement, as a binding material, consumes large amounts of non-renewable resources such as limestone and clay, as well as significant quantities of high-quality energy sources like coal during its production process ； In concrete production, a large amount of limestone is also added, and the economic value of the limestone resources consumed in these processes is far greater than that of the clay resources used for brick manufacturing. Furthermore, walls and frames are mostly solid; concrete has a high density and is used in large quantities, which not only wastes raw materials but also increases the weight of the building, thereby raising the costs associated with foundation preparation and construction. It can be seen that this structural system is not the most economical. If technical improvements are made to such building structures, such as increasing the strength of the concrete and raising the porosity of the walls, then once the goal of reducing the use of concrete is achieved, such systems should be included in the list of wall (building system) types that are encouraged and supported for development. Therefore, the purpose of redefining new types of wall materials is to guide work through scientific management methods, and to use macro-control measures that conform to the laws of objective development and market economy principles in order to help wall material companies achieve healthy and sustainable growth. Only by properly understanding new wall materials and building energy efficiency standards and ensuring their full implementation can the promotion of such materials and energy-saving measures in buildings proceed smoothly.