小模块·半预制·高性能——瑞士既有住宅的装配式节能改造研究

Small-Module,Semi-Prefabrication,High-Performance:Swiss Prefabricated Energy Retrofit for Existing Residential Buildings

在我国“双碳目标”与“城市更新”的双擎驱动下,面向既有住宅的节能改造议题重新唤起社会与业界的广泛关注。然而,单一采用传统围护改造技术普遍存在系统整合度低、施工周期长、建造品控难、环境与住户干扰大等问题而无法实现可持续效益最大化。对此,本研究立足于轻型装配式技术与住宅节能改造的融合潜力,援引欧洲50号项目(ANNEX 50)的瑞士体系为核心案例,提取其“小模块”“半预制”“高性能”三大围护改造策略,进而针对围护预制模块的集成化、适应性、性能化展开深入解析,据此为我国城镇住宅开展轻型装配式节能改造提供参考与建议,以推动我国建筑行业的可持续转型。

With the acceleration of China’s urbanization process,the stock of urban housing has developed rapidly.Currently,34.5%of urban residences are over 20 years old with poor construction quality and low energy standards,becoming a critical obstacle to achieving the“dual carbon”goals.Although China has attached great importance to residential energy retrofit in recent years,there are still certain limitations compared with Europe,especially in single retrofit action with low systematic integration,reliance on on-site construction leading to severe environmental pollution,and relatively low energy-saving and carbon-reduction goals.In contrast,some European countries have turned to more comprehensive sustainable renewal since the beginning of this century and successfully integrated the lightweight prefabricated technology and the nearly zero-energy building system into residential retrofit scenarios.Among these practices,there is no doubt that the ANNEX 50 project funded by the IEA ECBCS is the most representative.In this regard,this paper selects the Swiss practice in the ANNEX 50 project as the core research target and extracts its three key retrofitting strategies:small modules,semi prefabrication,and high performance.The“small-module”strategy refers to the use of small-scale standardized envelope modules,the core of which is the highly integrated design of multiple building systems.Taking the standard F4.1 façade module as an example,it is divided into four fundamental constructive layers:leveling layer,structural layer,thermal insulation layer,and finish layer,to integrate various functions such as structure,insulation,day lighting,ventilation,sunshading,waterproofing,air-tightness,and even building aesthetics,etc.Especially,it creatively integrates the mechanical ventilation ducts within the envelope module for supplying fresh air,achieving simultaneous improvements in indoor environmental quality(IEQ),space adaptation,and construction efficiency.The article also discusses the internal and external constraints of the modulus system for standard envelope modules.The“semi-prefabrication”strategy combines advanced lightweight prefabricated technology with traditional on-site construction systems.The former are usually used in retrofit areas with high performance and quality requirements or a high degree of standardization(e.g.walls with windows),while the latter are usually deployed in the envelope parts with large areas,relatively low-performance requirements,or non-standard dimensions(e.g.opaque walls),thus achieving the“quality-cost”balance.This paper further demonstrates the“module-base wall”,“module-module”and“prefabrication-non-prefabrication”connections to restore the whole process of the Swiss retrofit system,and also reveals how the standardized envelope modules are created based on extensive investigation and typology analysis of the existing housing stock,and how their variants can be further adapted to the market demands.On this basis,the study points out that the“standardization”of the Swiss retrofit system is to standardize the module design and construction logic in a broad perspective,rather than a narrower constraint down to specific dimensions.The“high-performance”strategy refers to the retrofitted residence’s achievement of the energy and performance goal set by the Swiss Minergie system,and the multi-performance design of the envelope modules.For thermal performance,the envelope module achieves effective insulation for ventilation ducts and base walls by using timber framework with low thermal conductivity and three-layered insulation system,reducing the heat transfer coefficient to 0.16 and 0.09 W/(m2·K),respectively,and eliminating the thermal bridging effect.The basic air-tightness of the envelope module is mainly achieved by the combination of gypsum fiberboard covering and pre-built flexible airtight coil lapping.And the air-tightness of ventilation ducts highly depends on the connecting joints with rubber collars.Besides,the Swiss system emphasizes the quality and duty of on-site construction to ensure final air-tightness and following maintenance.For fire protection,by combining the gypsum fiberboard and the non-combustible insulation materials in different ways,the Swiss EI30 nbb and EI60 nbb fire ratings can be achieved,aiming to prevent the structural failure of the timer framework of the envelope modules or the spread of flame through the ventilation ducts.For sound insulation,the Swiss system mainly uses insulation materials and gypsum fiberboard to control the vibration of ventilation ducts and the dynamic stiffness of the ceiling system,so as to achieve the effect of noise reduction and sound insulation.Finally,drawing on the Swiss experience with lightweight prefabricated energy retrofit,this paper returns to the local application perspective in the Chinese context and offer constructive suggestions in perspective of climate responsiveness,construction strategies,and working methods,aiming to promote the integration of prefabrication technology and nearly zero-energy system in the scenario of sustainable retrofit for existing residential buildings.