1 Forrest Place

HVAC D&C | Tenancy Upgrades
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Apex Technical Services where engaged by Primewest/Opra to completed all mechanical services for an Upgrade of Services at 1 Forrest Place. This works required the supply and installation of new Air-conditioning units within a limited space.

This works included the installation associated duct works and air-conditioning control system. The project required a redesign of AHU’s to fit over the floors effectively. AHU’s where delivered flat pack and built in the plantrooms.

General scope of works

The work contained in this specification and associated drawings for the mechanical services includes design coordination, engineering, preparation of workshop drawings, all site coordination, construction and installation, obtaining all relevant approvals and permits, commissioning, training, maintenance and warranty of the installed systems.

The nature of this project requires the Mechanical Contractor to take on certain design responsibilities to
ensure that the installation:

  • Can allow for a staged installation to minimise downtime to the current Level 2 tenants, who will occupy their tenancy while these works are carried out.
  • Maximises the functionality, performance, safety, flexibility and reliability of the mechanical services.
  • Is technically sound.
  • Can be constructed using currently accepted methods.

The work includes the following elements:

Testing and reporting on the existing installation

Prior to modifying the existing installation, the Contractor shall:

  • Prepare an as-installed drawing of the existing Level 2 and Level 3 ductwork. Allow to remove and reinstate duct insulation as required to accurately measure duct sizes. Also allow to remove and replace ceiling tiles as required. Insulation thicknesses and types shall be indicated on these drawings.
  • Test all existing AHUs serving Levels 2 and 3 for correct operation.
    • If the existing condition does not conform to the requirements in the contract documents, submit proposals to rectify the deficiencies with related costing, time and other impacts.
    • Subject to the rectification works on existing systems, achieve the performance in the contract documents.
  • Prepare a detailed record of the air and water balance figures, and report back any system faults.
  • Measure the following:
    • o Existing air flows associated with Level 3 and Level 4 plant.
    • o Existing CHW and HTW flows associated with Level 3 and Level 4 plant.
    • o Existing CHW and HTW flows through every pipe branch from the main CHW and HTW risers.
    • o Total flows and pressure drops.
    • o Total and static pressures at significant points in the system.
  • Make a record of the existing set-points and configuration of the system, including:
    • o All existing time schedules
    • o All temperature set-points, including (but not limited to) room temperatures and supply air temperatures
    • o Run-on time for after-hours AC activation.
    • o Static pressure set-points for VSDs.
    • o Motorised damper drive times (if applicable)
  • Submit this information to the Consultant before proceeding with the workshop drawings. Allow for a review period of 2 weeks.

New AHUs to serve Level 2 office space

Level 2 is currently divided into two tenancies. At least one of the Level 2 tenancies will be occupied while the mechanical upgrade works are carried out.

Both tenancies are served by a common constant volume multi-zone face/bypass AHU (AC-6) located in the western plant room.

AC-6 has four zones; three of which are serving the southern tenancy and the fourth serving the northern tenancy. AC-6 is connected to the building’s central thermal plant.

The works on Level 2 will generally be as follows:

  • Install new duct connections and dampers in the existing Level 2 S/A and R/A ductwork to facilitate the change-over from the old AHUs to the new AHUs. The Contractor shall take responsibility for determining the size and position of these connections to facilitate the staging process.
  • Provide four new AHUs to serve Level 2. A separate AHU will be provided for each thermal zone. These new AHUs will be located on Level 3. Carry out modifications to the structural supports and access platforms to accommodate the new AHUs.
  • The new AHUs will be custom-built downward discharge units to fit the project’s spatial constraints – the specific details are provided in Appendix A. The Contractor must finalise the AHU details with the manufacturer (as part of the workshop drawing process) before ordering equipment.
  • Provide 3-phase variable speed drives with differential pressure controls for all new AHUs.
  • Remove the existing AHU, AC-6, once the new AHUs have been installed.
  • Reuse the existing ductwork within the Level 2 tenancy space with the new AHUs.
  • Provide new supply air diffusers and transfer ducts as shown on the drawings, which will allow the northern tenancy to be served by AHU-L2-C. All works within the Level 2 tenancies must be undertaken after hours.
  • Provide pipework connections from the existing CHW and HTW risers to the new AHUs.
  • Provide a new Mechanical Services Switchboard (MSSB) on Level 2 and Direct Digital Controls (DDCs) for the new mechanical equipment.
  • The new DDCs shall be fully integrated into the existing BMCS by the incumbent controls contractor, including an update to the BMCS GUI to show the new equipment. The controls contractor shall be appointed as a subcontractor to the Mechanical Contractor. Allow all associated costs in the tender price.

New AHUs to serve Level 3 office space

Level 3 is currently vacant.

The main AHU (AC-7) is a constant volume multi-zone face/bypass unit located in the western plant room.

AC-7 has three zones and is connected to the building’s central thermal plant.

The downstream ductwork within the tenancy space has recently been painted. All supply air diffusers, cushion head boxes and flexible ducts have been removed.

The works on Level 3 will generally be as follows:

  • Remove AC-7 to make way for some new AHUs that will serve Level 2.
  • After the new Level 2 AHUs are commissioned, install three new AHUs to serve Level 3. A separate AHU will be provided for each thermal zone. These new AHUs will be located on a new structural platform adjacent to Level 4.
  • The new AHUs will be custom-built downward discharge units to fit the project’s spatial constraints – the specific details are provided in Appendix A. The Contractor must finalise the AHU details with the manufacturer (as part of the workshop drawing process) before ordering equipment.
  • Provide 3-phase variable speed drives with differential pressure controls for all new AHUs.
  • Reuse the existing ductwork within the Level 3 tenancy space.
  • A separate AHU will be provided for each thermal zone.
  • Provide pipework connections from the existing CHW and HTW risers to the new AHUs.
  • Provide a new Mechanical Services Switchboard (MSSB) on Level 3 and Direct Digital Controls (DDCs) for the new mechanical equipment.
  • The new DDCs shall be fully integrated into the existing BMCS by the incumbent controls contractor, including an update to the BMCS GUI to show the new equipment. The controls contractor shall be appointed as a subcontractor to the Mechanical Contractor. Allow all associated costs in the tender price.

Workshop/fabrication drawings

Submit the following detail drawings at minimum 1:50 scale or larger, showing:

  • Fire and smoke dampers including dimensional tolerances.
  • Floor wastes.
  • Ductwork, pipework and equipment layouts and sections. Show the location of fire rated building elements.
  • Diffuser and grille reference numbers corresponding to commissioning test results.
  • Riser layouts and sections.
  • Plant room layouts and sections.
  • Locations of automatic control sensors, motors and valves.
  • Acoustic details.
  • Conditioner construction details.
  • Seismic restraint details.
  • Piping and other schematic drawings including numbering of each valve to correspond to the valve tag notation. For refrigerant piping include slope of horizontal runs, oil traps, double risers and valving.
  • Submission drawings required by authorities.
  • Switchboard details.
  • Wiring diagrams.

Electrical loading information for mechanical services

Submit electrical loading information for all equipment along with the MSSB shop drawings.

Submit the information for items not supplied from the new mechanical services switchboards (MSSBs).

Submit details for motors with reduced current starting. Make sure starting characteristics are within the characteristics of the respective submain protection devices.

Submit the following information for each new MSSB:

  • Board location and designation.
  • Foreachsubmain connected to the board, submit the following for each item connected to it:
    • Submain designation.
    • Item designation and name.
    • Power rating in kW.
    • Number of phases.
    • Full load amps per phase.
    • Power factor.
    • Total amps on each phase for respective submain.

Equipment selections and calculations

Documented fan pressures and pump heads are based on provisional equipment selections and estimated pressure drops.

Before ordering equipment, calculate the respective system pressure losses based on the equipment offered and layouts shown on the shop drawings and submit the proposed selections.

Submit technical data for all items of plant and equipment. Include at least the following information in technical submissions:

  • Assumptions.
  • Calculations.
  • Model name, designation and number.
  • Capacity of all system elements.
  • Country of origin and manufacture.
  • Materials used in the construction.
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