The SIA 385/2:2025 standard is a crucial framework published by the Swiss Society of Engineers and Architects (SIA). It outlines compliance requirements for designing and implementing hot water installations in buildings, ensuring energy efficiency and hygiene.

Purpose and objectives

The primary objective of the SIA 385/2:2025 is to ensure safe and efficient hot water installations in buildings. This standard provides comprehensive guidelines on hot water demand, thermal losses, and energy efficiency to promote comfort and hygiene standards. It aims to minimize thermal losses in storage tanks and distribution pipes while addressing auxiliary energy requirements. By adhering to these compliance requirements, building professionals can enhance thermal performance, ensure energy conservation, and help prevent legionellosis, thereby safeguarding public health.

Scope: who must comply

The SIA 385/2:2025 compliance requirements apply to a wide range of stakeholders in the construction materials and buildings industry. This includes:

• Architects and Engineers: Professionals involved in the design and planning of hot water systems.
• Contractors and Installers: Companies responsible for the installation of hot water systems in residential, commercial, and industrial buildings.
• Building Owners and Developers: Entities that must ensure their buildings meet the specified energy efficiency and hygiene standards.

By following these guidelines, stakeholders can ensure that their hot water installations meet the necessary requirements for safety, efficiency, and comfort.

How SN 546385/2:2025 relates to other standards

The SIA 385/2:2025 is closely related to several other standards that complement its guidelines:

• SIA 385/1: This standard provides foundational principles for energy-efficient building design, relevant to hot water systems.
• SN EN 12831-3: This standard outlines methods for calculating the heating needs in buildings, which is integral to hot water demand assessments.
• SN EN 15316-3: This standard focuses on the economic evaluation of energy systems, particularly useful for analyzing hot water distribution systems.

Revision history and current status

The SIA 385/2:2025 was published by the Swiss Society of Engineers and Architects (SIA) in 2025. This latest revision includes updates to thermal performance criteria and clarifications on energy conservation measures. It reflects the evolving standards in building practices and energy efficiency requirements, ensuring that hot water installations are safe, hygienic, and efficient.