World’s greenest buildings | American Geophysical Union HQ

Supporting scientists measuring everything from glacier movements to volcanic activity, the AGU pledged to put the environment at the heart of its HQ renovation.

The result? Washington DC’s first net zero office retrofit.

Key features

• Huber heat exchanger, which transfers heat between the city’s sewer system and building
• 700 solar panels
• Rainwater collection
• Six-storey green wall connected to the building’s HVAC system
• Radiant cooling system pumping chilled water throughout building
• Smart glass windows made with SageGlass Lightzone

“AGU is the world’s largest organisation of Earth and space scientists,” says Janice Lachance, EVP, strategic leadership and global outreach, at AGU. “We are a community of more than half a million. And with that comes ambitious goals.”

Being “fully net zero energy” was the plan from the start of the renovation, which kicked off in 2017 and finished in 2021 after some pandemic-related delays. The renovation focused on four themes: reduction, reclamation, absorption and generation.

Reduction

The building has a network of pipes in its ceiling panels, circulating cool water and absorbing heat generated by people and equipment.

A six-storey living wall of plants further cuts pressure on the HVAC system by filtering indoor air instead of pumping it in from outside and then adjusting its temperature and humidity. An air quality management system checks whether the filtered air is cleaner than outdoors before pumping it back into the building. AGU says the green wall reduces the building’s energy needs by up to 30%.

Some 929 smart windows control daylight, heat and glare. These are connected to the building’s lights, allowing them to optimise indoor lighting throughout the day.

Reclamation

The AGU HQ collects rainwater, which – after being purified – is used for all non-potable water needs. “All exterior plants are watered with reclaimed water, toilets flush with reclaimed water and our green wall is kept running with reclaimed water,” says Lachance.

By reusing rainwater, the building is able to cut both utility bills and alleviate some pressure on the city’s water treatment system.

Absorption

“All of the systems are impressive, but the Huber system is probably the biggest achievement in terms of its novelty and its ability to take advantage of an untapped resource in DC,” says Lachance.

The Huber system, the first in the US, enables the building to take warm energy and transfer it into the sewer system – or vice versa. The system also connects to the network of pipes in the ceiling panels, allowing it to use wastewater when the sewers are cool to absorb heat in the building, thereby reducing energy use further.

Generation

The AGU HQ has 700 solar panels. On sunny days these will generate more than 100% of the building’s energy needs, with the surplus sold back to the city’s energy grid.

Typically, buildings would have to convert the grid’s alternating current (AC) to direct current (DC) in a process that reduces energy efficiency by up to a fifth. With its solar panels generating DC power, the AGU HQ has to tap into the grid’s AC power only when it needs to top up the building’s own generated energy.

AGU’s tech policy

AGU relied on external experts in sustainability, technology, building renovation and climate science to steer the design of the building. But Lachance says AGU had three criteria for those experts when deciding what tech to use in the building:

• Technologies implemented must have already been seen to be effective in the field: new technologies were fine, but experimental ones were not
• Individual technologies must work in sync with each other to maximise efficiency
• The effort to implement a new technology should be as low-impact as possible when it comes to environmental impact.

What could AGU improve further?

Solar panels evolve so quickly that the equipment the building uses is already a little out of date. Lachance says: “AGU probably could have waited a little longer before their purchase and ended up with slightly more efficient panels.”

Regardless, AGU has not made any significant changes since the building opened. Instead, the organisation is focused on further optimising its new systems. “For example, our engineer was able to fully heat and cool the building during portions of the spring just by controlling the amount of solar energy that was allowed though the building’s windows,” Lachance says.

Results

• 96 points under LEED’s framework for new construction – the highest at the time for a commercial building in Washington DC
• Energy Star Certified score of 93, one of 18 buildings in the city to reach that level and 20 points higher than the average office in the city
• 47% fewer greenhouse gas emissions per sq ft than the average office in Washington DC

Thanks to its solar panels and energy saving measuring, the building can, on average, handle the full energy load that it needs. While the building does need to tap into the grid on days where there is not enough sunlight, AGU says that “over-production days” and “under-production days” cancel each other out over the course of the year.

How much that will reduce cost is still unclear, however. Manufacturing delays have meant that the building’s energy meters were only installed in early August this year. Projected estimates suggest the HQ will save between $2,000-$3,000 per month on average.

As a project centred on sustainability, the AGU HQ renovation is about more than simply hitting targets, impressive though they are. Lachance says: “This is a living, breathing reminder for our staff and our visitors of how not just to imagine a greener way to live and work but to actually go out and make it a reality.”

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