Energy is the vigor of the universe. Literally the ability to do work, little can happen without energy. Whether deriving from the heat and illumination carried by the sun’s rays or the chemical energy produced in our bodies to carry out an assortment of biological tasks, energy is rampant throughout the earth. Even in the home, as residencies need to maintain an optimal air and water temperature and air quality, energy efficiency is a key interest.
ANSI/ASHRAE 90.2-2018: Energy-Efficient Design Of Low-Rise Residential Buildings, an American National Standard, establishes the minimum whole-building energy performance for energy efficient residential buildings.
While any energy-efficient addition to a building can be favorable, it is often ideal to consider the whole building when designing and building or renovating a house. Much like how the environment is shaped by energy-dependent systems influenced by interconnected, contingent components, an entire home or building comprises a system influenced by a variety of variables, such as local climate, insulation, water heating, windows, and other factors within the building envelope.
ANSI/ASHRAE 90.2-2018 covers the design, construction, and verification for new residential buildings and their systems, as well as new portions of existing residential buildings and their systems that use renewable and nonrenewable forms of energy. Specifically, for one- and two-family dwelling units, multifamily structures of three stories or fewer above grade, and outbuildings, this standard offers guidance for the building envelope, HVAC and related systems, service hot-water systems, major appliances, lighting systems, snow and ice melt systems, and pools and spas.
Please note, however, that ANSI/ASHRAE 90.2-2018 does not apply to specific procedures for the operation, maintenance, and use of residential buildings or transient housing (e.g. hotels, motels, nursing homes, jails, dormitories, and barracks).
ANSI/ASHRAE 90.2-2018 revises the 2007 edition of the same American National Standard. This revision is substantial, as it offers a completely new approach to delivered residential building energy performance. According to the foreword of ANSI/ASHRAE 90.2-2018, the leadership standard “seeks to deliver residential building energy performance that is at least 50% more efficient than the energy efficiency defined by the 2006 IECC.”
To meet this objective, ANSI/ASHRAE 90.2-2018 has undergone the following changes:
- New definitions were added to support the proper performance modeling, energy analyses, and use of the standard.
- The standard clarifies which elements apply to new construction, additions and alterations.
- Guidance for additions and alterations was moved to new Section 5.
- Added international climate data from ANSI/ASHRAE 169: Climatic Data For Building Design Standards when using this standard in climates outside the U.S.
- For prescriptive tables of envelope performance data used for on-site power generation and compliance modeling, new clarifications address mass wall guidelines in warm, humid climates, and heated slabs.
- Performance specifications for ground-source heat pumps were added.
- Alterations clarify the minimum lighting efficiency provisions for single-family, large single family, and multifamily homes.
- New guidance was provided for verification of envelope airtightness, mechanical ventilation in single-family and multifamily structures, and on-site power systems.
- Section 9.1, “Compliance Reporting,” was revised to place an emphasis on key building data and reports (energy modeling, load calculations, on-site power systems performance, envelope, appliance loads, and mechanical, lighting, and water systems components) necessary for compliance determination.
- Additional clarifications to software guidance were added to encourage software developers to develop and deliver software that has accurate, repeatable, and comparable results. These clarifications were added because ANSI/ASHRAE 90.2-2018 highly prioritizes guidance for modeling software.
- New normative Appendix D, “Installation Requirements,” was added to address proper installation techniques for critical components of buildings that provide thermal resistance.
- Clarifications were added to address lighting modeling and multizonal building air-leakage testing procedures.
ANSI/ASHRAE 90.2-2018: Energy-Efficient Design Of Low-Rise Residential Buildings is available on the ANSI Webstore.
