Keeping a Passive Building Cool Without Losing What Makes It Special

OUR INSIGHT

The answer wasn't air conditioning - it was understanding why the building was struggling and finding a solution that worked with its passive design instead of against it.

The Challenge

The Nueva School's Hillsborough library was built in 2001 as a bioclimatic building, no mechanical cooling by design. Operable windows, high thermal mass, a green roof, and in-slab radiant heating kept it comfortable for years. Then came a renovation adding four new classrooms, and after a string of hot summers, teachers were asking for AC. The question for LMS Architects: how do you respond to legitimate comfort concerns without dismantling a building that works the way it does for a reason?

Our Role

We ran a rapid thermal comfort and energy analysis using recent weather data to model what was actually happening in the building on hot days, and what would happen under several intervention options. Limited ceiling space, minimal rooftop area, and a strong desire to preserve the building's low-energy character ruled out conventional AC. What the analysis identified instead: condition only the fresh air supply on the hottest days, and add automated night-flush control to pre-cool the thermal mass overnight. We worked with the school to explain the tradeoffs and build confidence in a solution that didn't look like standard HVAC.

The Result

A hybrid system roughly one-third the size of a conventional air-conditioning installation, no costly structural modifications, no compromise to the building's passive identity, and meaningful relief during extreme heat events. The original bioclimatic design remains intact, now augmented rather than replaced. It's a working example of how analysis can reconcile passive architecture with evolving comfort expectations, rather than treating them as incompatible.

Services

Thermal Comfort Analysis | Rapid Building Energy Modeling | HVAC Sizing Assessment | Passive Cooling Strategy

• OWNER: Nueva School

• ARCHITECT: LMS Architects

• LOCATION: Hillsborough, CA

• YEAR: 2024

• SIZE: 4,100 sf