Bright Green Strategies: Residential Buildings, California

Date Published

2nd Dec 2020

Suzanne Wallace
Media & Communications Manager, IES

Since investing in IESVE, Bright Green Strategies working alongside David Baker Architects, has used the software to carry out comfort & overheating analysis and energy modeling & electrification analysis on a number of projects. 

This case study provides an overview of three California residential projects, giving insight on the use of IESVE to improve occupant comfort and energy efficiency. Cooling was not planned for any of these projects, which is why overheating studies were necessary for each. 

The standard used to compare against in all three projects is ASHRAE 55‐2017. This standard provides a framework to project teams seeking to define and qualify the definition of overheating. 

1950 Mission, San Francisco

This project consists of two connected residential buildings with a total of 157 units. The ground floor is comprised of retail and community areas, whilst floors 2‐9 are entirely residential units.

Bright Green Strategies used the IESVE to model this residential block and evaluate which units were overheating, and analyse possible solutions.

Shown below are the indoor air temperatures for units on September 20th, the warmest day for most units. 

The Bright Green strategies team discovered that 1950 Mission did exhibit some characteristics of moderate overheating, with the warmest units, generally those on top floor and facing south and west, reaching temperatures in the upper 70s to low 80s during the hottest days of the year.

ASHRAE Standard 55‐2017 gives an ideal range of values for the project to fall into and some units do regularly exceed these values, however not severely.

The team was able to successfully use IESVE to study sunshades, where they were needed and where they were not, to limit the overheating while saving costs on the project.

500 Turk, San Francisco

This project is a single residential building with a total of 108 units. The ground floor is comprised of retail, community areas, and a few residential units. Floors 2‐8 are all residential units.

Again the Bright Green Strategies team used IESVE to evaluate which units, if any were overheating, and analyse possible solutions.

For this project, it was discovered that overheating wasn’t a particular issue with the results showing all units, even the worst case, meeting the standard throughout the summer months. This provided validation that the design met the ASHRAE 55-2017 standard. 

45 & 47 Midway Drive, Daly City

These two residential buildings comprised a total of 147 units. The ground floor consisted of community areas and a few residential units. Floors 2-4 are all residential units.

For this project, as well as studying the possibility of overheating, Bright Green Strategies also used the VE to conduct detailed energy modeling and electrification analysis.

Shown below are the indoor air temperatures for units on June 30th, the warmest day of the
year for most units. 

It was discovered that Midway Phase 1 was moderately overheating in some units. The analysis results showed that the most effective solutions would be Ceiling fan operation, which nearly brings all units into compliance.

As the building is all electric, the energy modelling conducted included a detailed analysis of the electricity systems to ensure they would work as expected and that they were modeled correctly in order to achieve an accurate result. 

The project team were interested to see what it would take to meet net-zero targets and be on track for the Architecture 2030 challenge. Bright Green Strategies investigated and monitored this throughout the projects design, and although highly energy efficient, the project just fell short of these.

The project demonstrated a site energy use intensity (EUI) of 12 kBtu/ft2 and met compliance for California’s energy code, Title 24. To achieve this relatively low EUI score, the team analyzed several different mechanical systems, envelope types, and plan to install a large 292 kW PV system on the project's roof.

“At Bright Green strategies we offer LEED and GreenPoint rated certification services as well as Title 24 energy analysis. While Title 24 is required for energy compliance within California, many of our developers and architects are looking for a tool that can give more accurate, real-world results. IESVE allows us to create detailed models by diving into items such as solar analysis, mechanical system specifics, and even occupant behaviour. Released from the limitations of compliance software, IESVE allows us to provide our clients with much more meaningful and accurate results. All of this allows us to make more informed decisions during design and ultimately create a building that is comfortable for occupants and sustainable for the world.”

Steve Davis, Project Manager, Bright Green Strategies
 

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