This article is the third part of a multi-part series looking into the world’s greenest buildings. It is based off the book of the same name by Yudelson and Meyer. I thought the book was really good and the last two parts have been well received.

Great River Energy Headquarters

Out of all the case studies in this book, this one jumped out for its commitment to generating energy on site. This is not surprising as the owner and occupant is an energy company.

The Great River Energy Building is located in Maple Grove Minnesota. It was commissioned by its owner Great River Energy, who are the second largest electricity supplier in Minnesota.

At the origins of the building there was an ambition to push the boundaries of sustainable design and construction. As an energy company, they wanted the new headquarters to be a showpiece of efficiency and to contribute to an evolution in green design.

 As the building was in an out of town location, the company negotiated a deal with the local transport authority to allow employees to park at the old office and get a bus to the new office. Out of town campuses allow a degree of space that can make on site renewable electricity generation possible. But can increase transport costs for employees, this solution resolved that.

The building comes equipped with some really impressive features to deliver on their energy efficiency ambitions.

One of these was daylighting. To maximise this, the building’s long axis runs east-west, orienting most of the glass to face the north and south, reducing solar gain on the east and west sides.

The need for artificial lighting is recued further by having narrow floor plates that allow daylight to reach the building’s core.

Further measures include atriums that bring light into the centre, walls are lower to facilitate more light reaching workstations and windowed interior walls bring in natural light from the perimeter. There is also a whole host of smart lighting technologies to further reduce electricity demand for lighting as well as high performance window coatings.

These all contribute to a 40% reduction in lighting energy demand.

One unique feature that the building has is a lake-source geothermal heating and cooling system, combined with underfloor displacement ventilation.

Interestingly, the lake is man made. The system works to extract heat from the building in summer and absorb warmth from the lake in the winter. The building has 70 heat pumps, which is the main mechanical system. Despite the conditions in Minnesota, the building does not have a chiller or a boiler.

The building also has an eye catching 200-kW wind turbine, combined with solar arrays, mounted both at ground and roof level, which together generate 6% of the building’s energy.

The building comes equipped with a highly intelligent building management system. This monitors lighting levels, temperature, CO2 concentrations, and occupancy levels and adjusts accordingly to minimise the amount of energy required. This contributes to the overall reduction in energy use of 40%.

The plumbing system uses rainwater harvesting and low flow fixtures to reduce water use by 74%. There is a 75,700L underground cistern that collects rainwater and snow melt for the building.  This water is then sanitised and use for toilets and urinals.

Post occupancy the building underwent a lengthy 2-year commissioning period to make the necessary adjustments and to understand the building’s performance under real life conditions.

The building was able to achieve the following energy performance. It has a total annual energy use of 3,086,814 kWh with an intensity of 200 kWh/sq m.

What you need to know   

This article is the third part in a multi-part series where I am picking out my favourite sustainable buildings from Yudelson and Meyer’s book The World’s Most Sustainable Buildings.

Today was the turn of looking at the Great River Energy Headquarters building in Maple Grove Minnesota.

This building stands out for its commitment to generating energy on site. The lake-source geothermal heating system and rainwater harvesting systems are also very innovative and effective.

As an out of town office building the looks are not as important as the footfall close to the building is not that high. That being said, I find the wind turbine and solar arrays eye catching and they more than make up for the box like nature of the building.

The building makes use of a number of sustainable design techniques to make real energy and carbon savings making it a highly sustainable building.

Thank you for reading,

By Barnaby Nash

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