Behind the Scenes of The New Horton’s Green Design Innovations

Downtown San Diego’s once-iconic mall aims to become a mecca of sustainability with solar heating and blackwater system cooling   
The mid-construction view of the interior of the former Horton Plaza mall.

Horton Plaza was once a local and national icon. Opened in 1985, its phantasmagoric interior design was hailed as radically new. The mall was an instant financial success; suburbanites rushed downtown to patronize its retail tenants.

The one-million-square-foot, urban ode to big-box shopping is gone. It’s being replaced by a $1-billion mixed-use project that’ll pair ground-floor retail with office and life-sciences space. Projected opening date: Summer 2024.

The San Diego Sun recently chronicled a walking tour of the current construction site, the new retail layout and plans for a revamp of Horton Park. 

Here’s a follow-up on details about massive sustainability efforts being baked into the design. It’s a story of adaptive reuse of the old infrastructure, solar heating and blackwater-system cooling.

My walking tour was hosted by Stockdale Capital Partners LLC director of culture programs Jimmy Parker, RDC senior principal Sean Slater and Introba principal Calina Ferraro.

Introba and Ferraro are overseeing the greening of Horton.

“The sustainability vision from Stockdale has been a core principle since the beginning of the job,” Ferraro says. “We all want to prove you can do a high-performance, developer-driven project that’s sustainable and commercially successful.”

Three aspects of the design are paramount to that goal: adaptive reuse, heating and cooling.

Horton construction site hosts Calina Ferro, Sean Slater and Jimmy Parker.

Adaptive reuse. The former Horton Plaza’s primary structures didn’t get completely demolished and have to be rebuilt, Ferraro says. “All the energy and carbon that went into making the concrete and steel is carbon that was saved,” she says. “Based on calculations, we started the project with a 60% reduction in carbon emissions.”

In other words, the environmental benefit started with the “adaptive reuse” decision to not start over from scratch, but to reuse and repurpose 60% of the building materials already in place.

“Once we saved as much as possible, we modernized the face of the project with a high-performance envelope,” Ferraro says. “There’s a thick layer of insulation. It’s a high-performance glazing that will require as little heating and cooling as possible.” 

Heating. With the exception of a few kitchens that will use gas, the backbone of the central heating system is electric. The system is supported by the widespread use of photovoltaic (solar) panels.

“We’ll have a cutting-edge microgrid on the rooftops of the buildings and up over the mechanical systems,” Ferraro says. “We’re maximizing the amount of space where we can put solar panels.”

The solar panels are designed to generate electricity for Horton. They’ll be partnered with two large battery banks. Solar power can be stored from the day and used to offset energy use in the evening.  

Cooling. To maximize reuse of water within Horton, there will be a central channel that leads to an onsite treatment room for both greywater and blackwater

To be clear: Greywater comes from things like shower usage or washing machines. Blackwater comes from toilets, sinks and dishwashers. The Horton team calls this the “Ew, But Cool” factor.

“Water will drain into the system,” Ferraro says. “It’s a multi-step process with six or seven stages, finishing with the final disinfectant. This is NOT for drinking water. We’ll be reusing this treated water to flush out our cooling towers.”  

The savings will be substantial–more than half of campus water used, Ferraro says, noting that all the operations are performed underground and out-of-sight.

Ferraro says that within San Diego, Horton will have one of the largest non-residential water treatment systems that’s not an industrial plant.

“It’s better land-use,” she says. “We not only didn’t knock this building down, we’re making it more sustainable in its own footprint.”  SDSun 

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