GREEN LEAF ENGINEERING

St. Mary Magdalene, Islington

As part of the PSDS Phase 3a schemes, Green Leaf Engineering were employed by Surveyors to Education in to carry out the design, supply, installation, and commissioning of 800Kw of primary heating plant at Saint Mary Magdalene Academy, Islington.
As part of the PSDS Phase 3a schemes, Green Leaf Engineering were employed by Surveyors to Education in to carry out the design, supply, installation, and commissioning of 800Kw of primary heating plant at Saint Mary Magdalene Academy, Islington.

INTRODUCTION

The proposal consisted of the replacement of the existing gas fired boilers, with air source heat pumps configured in a hybrid system with gas boiler backups. The scheme consisted of two plantrooms spread across the site each with individual requirements for LTHW ASHP installations. Works commenced from our appointment in January 2023 and were completed in April 2023 including commissioning, client training and handover of site to the school. The below case study will detail the technical requirements on site, processes and involvement from Green Leaf and challenges faced with solutions proposed by us as the MEP Contractor.  

SCOPE OF WORKS 

Below Ground Plantroom The existing LTHW Boiler in conjunction with domestic boiler to generate local LTHW to serve the DHW cylinders were isolated, stripped out and replaced with 1 No ASHP capable of delivering 400Kw combined thermal load. In conjunction with this, the necessary circulation and shunt pumps along with additional buffer vessels were installed. To control the new installation, the existing BMS system was validated and then altered to accommodate the new installation. 

Roof Level Plantroom The existing LTHW Boiler in conjunction with domestic boiler to generate local LTHW to serve the DHW cylinders were to be isolated, stripped out and replaced with 1 No ASHP capable of delivering 400Kw combined thermal load. In conjunction with this the necessary circulation and shunt pumps along with additional buffer vessels were to be installed. To control the new installation, the existing BMS system was first to be validated and then altered to accommodate the new installation. 

TECHNICAL DESIGN

The initial design pack issued identified that 2 blocks, Main Block and Basement Plantroom could be reconfigured to include AHSP with Gas Boiler top up to achieve the desired heating loads. The loads required are detailed below. ·Main – 360Kw – LTHW only serving radiators, fan heaters and new underfloor heating. ·Below Ground plantroom – 300kw to serve existing underfloor heating. Through discussions with various suppliers in the Heat pump market, it was determined that Carrier Caleo were best placed to provide a fully compliant system utilizing their 400Kw Heat pump unit with integral buffer vessel and controls. Data can be provided upon request. 

DETAILED DESIGN

As part of the project, Green Leaf were employed on a design and build basis to produce a RIBA Stage 4 Detailed MEP Design for this project. Green Leaf carried this out utilising both our inhouse design team in conjunction with our MEP design partner Wilson Grey. The design works that were required within Green Leaf’s scope to take it from the contract award at RIBA Stage 3 and project commencement at RIBA Stage 4 were as follows: Electrical LV Cable Sizing / LED lighting Calcs for replacement as VO / LV Distribution Design Mechanical System sizing and configuration including pipe & valve sizing / ASHP Selection and control philosophy / Buffer Vessel Sizing. Construction Structural Report for builders works / MEP Plinth Design & Detail / Scaffolding Design / Temporary Works Designs including firestopping & trenching details.