KLON-06 Phases 1-4

Mechanical & Electrical Engineering Services

As part of the continued expansion of Kao Data’s KLON-06 data centre, Gratte Brothers | Building Services & Engineering was appointed as General Contractor to deliver four new data halls within a live operational environment. Delivered across four phases, the data centre expansion added 12MW of IT load, encompassing design and build, mechanical and electrical services, commissioning and technical fit-out.

Project Information

Client:
Kao Data
Main Contractor:
Gratte Brothers
Sector:
Data Centres
Duration:
36 months
Services:
General Contractor, M&E, CSA, Fit-out

The Brief

Kao Data’s KLON-06 facility in Slough Trading Estate provides 20MW or Tier 3 equivalent co-location, representing a sizeable and scalable option for continued enterprise or cloud deployments. All capacity operates to an SLA-backed PUE (power usage effectiveness) or 1.25, and all IT-load powered by 100% renewable energy.

Gratte Brothers | Building Services & Engineering was tasked as General Contractor to expand the existing operational data centre, converting the fallow space into 4 additional data halls with a total IT load of 12MW. The design, build, and fit-out – which included the hot & cold aisle containment for the white space – brought the 30,000m2 of technical space online.

Phase 1 was competitively tendered, with phases 2, 3 and 4 all negotiated with an open book approach, demonstrating competitiveness, programme and commissioning benefits during each design stage ahead of final client sign-off.

Key Project Features:

  • 12MW total IT load installed across four phases.
  • Hot and cold aisle containment within the white space fit-out.
  • Colour-coded low voltage (LV) busbar systems to support clear identification and maintainability.
  • Dual power supplies supported by seven high voltage (HV) generators providing over 12MW in total.
  • A prefabricated chilled water package plantroom designed and built in-house.

Design Principles

Phases 1-3 followed a consistent system design and layout. By applying lessons learnt in real time, we refined and optimised the MEP (mechanical, electrical, plumbing) strategy at every stage. Colour coded LV busbar systems were adopted throughout to provide immediate visual identification of power streams and enhance maintainability. Phases 1 & 2 incorporated four switchrooms; Phase 3 including three. All three phases are cooled via air-source heat pumps (ASHP), feeding CRAH (computer room air handler) units and adiabatic IEC (indirect evaporative cooling) units.

Phase 4 introduced a chiller-based cooling strategy, with chillers feeding fan wall units and CRAH units through a chilled water system. This represented a significant change from the earlier phases and required a revised approach to design, installation and commissioning.

The change was driven by the physical constraints of the building. Unlike previous phases, Phase 4 did not have the external walls or louvre arrangements needed to support indirect adiabatic cooling. The design was therefore adapted to incorporate seven fan wall units and a chilled water solution better suited to the available space.

This shift impacted far more than plant selection. It required close coordination across design, installation and commissioning teams, as well as collaboration between multiple professional disciplines throughout the project.

Prepackaged Plant Room

As part of Phase 4 at Kao Data KLON-06, we designed and built our first chilled water package plantroom at our Chelmsford prefabrication facility. The plantroom was designed by Gratte Brothers | Building Services & Engineering and Design & Coordination, built by our in-house team and delivered to site in two sections for connection on site.

The programme benefit was significant. What would typically take a supply chain partner 25–30 weeks to construct was completed by Gratte Brothers in 10 weeks.

The Benefit of Prefab

This was more than an off-site build. It was a carefully planned engineering solution designed around programme, logistics, safety and quality. Internal project material confirms the plantroom was constructed at Chelmsford, split into two sections to accommodate logistical constraints and planned around the physical split so it could be integrated once on site.

The off-site approach delivered several clear benefits:

  • More control over quality in a dedicated manufacturing environment.
  • Reduced complexity and disruption on the live site.
  • Programme protection by decoupling the plantroom build from wider site activity.
  • Reduced site risk by moving more work into a controlled off-site environment.

Power & Data Supply

To safeguard against outages and maintain operational resilience, the facility was designed with dual power supplies, supported by seven HV generators providing over 12MW in total. Each generator is supported by its own switchroom, with largescale external exhaust systems.

The site features multiple substations feeding the main HV intake switchrooms. These split the HV supply into dual feeds for the switchboard panels before conversion to LV for distribution throughout the building.

CRAC units within the switchrooms operate on both condenser water and internal refrigerant, processing four litres of water per second – automatically doubling to eight litres per second upon failure of a paired unit.

All pipework for the dry air coolers and condensers was prefabricated in-house using stainless steel, improving quality control and delivery speed. Four new technical suite switchrooms – each featuring uniquely colour coded LV busbar systems – showcase the high standard of engineering delivered by our team.

Compliant Delivery

All works were completed in full compliance with building control requirements and fire related legislation. Our temporary works team provided bespoke scaffold solutions, excavation oversight and site setup planning to ensure safe, controlled delivery across all phases.

CSA Delivery

Our CSA (civil, structural & architectural) scope included:
• Structural steel installations
• Construction of an elevator shaft and stairwell
• White wall and ceiling fit-out
• Riser cupboards
• Roof and cladding modifications
• Specialist floor coating
• Office area fit out
• Groundworks

Life Cycle Works

While on site at KLON-06, we also completed a range of supplementary works within the existing live operational tenant areas, maintaining 100% uptime. This includes:

  • Sidestream filtration replacement of traditional and glycol systems, including new copper pipework, controls and power feed alterations.
  • Replacement VESDA (very early smoke detection apparatus) panels with new network graphics head end.
  • CRAH & AHU (air handling unit) validation survey works.
  • Replacement of fire alarm panels with new network to link existing with new panels across the whole building which required a new headend graphics and software installation.
  • External vehicle access gates including BWIC (builder’s work in connection), electrical feeds, new controls and interfacing with intercom & access control systems.
  • Replaced all existing dosing pots with stainless steel.
  • Temporary chiller installation.
  • Provided ROM (rough order of magnitude) and programme advice with three options to replace all UPS and battery systems, obtaining and vetting four preferred specialist manufacturers.

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