Providing chiller technology to innovation hub

BOTSWANA: Four Climaveneta chillers are to be incorporated into a new high-tech innovation centre in Botswana.

The Botswana Innovation Hub (BIH) presently under construction is strategically located on a new 57 hectare innovation park near the Sir Seretse Khama International Airport in Gaborone, the capital city and business centre of Botswana.

The Hub will provide state-of-the art facilities to attract domestic, regional and global knowledge-intensive high-tech innovation companies.

This new 46,000m² building of futuristic appearance consists of three multi-storey blocks (referred to as bars), sharing a common podium housing a 23,000m² semi-enclosed basement carpark and service plantrooms beneath. The bars are interconnected by single and two-storey link bridges, which both span and enclose landscaped amenity gardens

As part of the building’s sustainability drive, an undulating green roof provides home for indigenous grasses, whilst further merging the building form into the surrounding site’s landscaping. Feature roof overhangs, favourable building orientation, a highly bespoke façade, courtyards accommodating the amenity gardens and extensive horizontal bris soleil structures all combine to provide the building with extensive passive solar shading. These features are further enhanced by a high performance building façade, low water usage faucets and a strategic collection of surface water for irrigation purposes.

The building is designed to exploit the benefits of exposing the building’s structural thermal mass to moderate the internal environment within recognised thermal comfort criteria. This is achieved by effectively circulating a conditioned air supply through exposed TermoDeck proprietary hollow-core concrete slabs, which form the floors and ceilings/roofs of the building structure.

At BIH one of the main savings is in maximum electrical demand charges, as the concrete slab is pre-cooled during the night (also using the free-cooling, when suitable outdoor temperatures prevail), which assists in greatly reducing the amount of cooling required during normal working hours in Botswana’s predominantly hot semi-arid climate, where summertime temperatures can exceed 40°C.

As a result, the maximum daytime peak power consumption associated with air conditioning and ventilation can be reduced by up to 50%, compared to similar buildings using conventional air conditioning and construction methods in Botswana.

These energy savings are reflected in the capacity of the central cooling and heating plant located in the super-basement energy centre, along with electrical switchgear and water storage tanks. Both chilled and heating water is generated by a combination of three Chillventa Integra multi-purpose ERACS2-Q XL-CA 2722chillers and one high efficiency air cooled chiller i-FX (1+i) CA 2722.

These machines provide the building with a total space cooling and heating capacity of up to 2,477kW and 1,764kW respectively. All the units can operate at full load in parallel to meet the peak cooling loads. This arrangement allows for one machine to be off-line for repair or maintenance, whilst still being able to meet the building’s cooling load throughout most of the year. The multi-purpose Integra units are able to operate in either cooling-only, cooling with simultaneous heating (this operating mode will be used predominantly during mid-season, giving EER’s of up to 9.3) and heating-only mode depending on the prevailing cooling/ heating loads of the building.

The i-FX (1+i) CA 2722 chiller is primarily used when peak cooling loads are required, however all the units are operated on a lead-lag duty share basis. The four Climaveneta machines work with a four-pipe variable primary and secondary chilled and heating water circuit pipework arrangement.