Greengage supported Dorrington in decarbonising Hamilton House, assessing its performance using the UK Net Zero Carbon Buildings Standard and preparing a pathway for achieving net zero aligned status.
Dorrington is a London-centric, independent, family-owned investor and developer with a residential and commercial property portfolio of around 80 assets. The company is looking to achieve net zero carbon across its portfolio by transitioning its assets to high energy performance standards. This strategic approach enhances the market positioning of its properties, providing a competitive advantage, attracting high-quality tenants, and increasing asset value for rental and sale.
Greengage was commissioned to carry out net zero audits for 10 office buildings, including Hamilton House, to decarbonise their commercial portfolio, assess transition risk, and reduce operating costs. These buildings vary in vintage and lease type, with differing levels of operational control.
In addition to the net zero audit, Hamilton House was submitted to the UK Net Zero Carbon Buildings Standard’s (hereafter, the Standard) pilot testing programme. This case study focuses on Greengage’s findings to enable Hamilton House to achieve the Standard’s ‘Net Zero Aligned’ status, subject to verification.
Hamilton House is a Grade II listed heritage office building in Central London. Dorrington acquired the property in 2018 with the intention of refurbishing it into a modern business centre offering flexible office space, while maintaining control of whole-building systems. After the acquisition, Dorrington carried out a programme of refurbishments until 2024, including the removal of gas through the installation of VRF systems, upgrading LED lighting, improving interior finishes and installing a sensor-based energy monitoring system that provides energy data by floor and end-use.
Credit: Dorrington
A net zero audit assessed Hamilton House’s alignment with the Standard. The objective was to determine whether the building could meet the Standard’s requirements, compile supporting evidence, and prepare for verification of its net zero aligned status. The audit involved collecting data across all relevant aspects and using it to calculate the metrics and information required to meet the Standard. The detailed scope of works included:
- Baselining and net zero gap assessment – Assessing performance against operational energy limits and other aspects of the Standard to determine whether the building could achieve ‘Net Zero Aligned’ status in 2025.
- Energy performance analysis – Using sensor-based energy monitoring data to analyse end-use and floor-wide energy consumption, voltage, and power factor.
- Site audit and property manager survey – Conducting a detailed walk-through of all areas, recording a detailed inventory of MEP systems, building envelope condition and systems, operational schedules, and installation dates. A survey with the property manager collected information on existing operational practices and occupier engagement.
- Identifying measures for energy reduction and on-site renewable energy generation.
- A cost–benefit analysis, including capital costs and operational savings for each measure.
- Providing recommendations to achieve compliance across applicable aspects of the Standard.
- A retrofit implementation plan with a timeline for implementing the proposed measures and verifying against the Standard.
Findings
- The gap assessment showed the building met most applicable aspects of the Standard except on-site renewable energy generation, as no rooftop solar PV system is currently installed (Table 1). A feasibility study confirmed solar PV potential, although installation and capacity for a heritage building would be subject to planning approval, which would be a valid constraint for a reduced renewable energy target. Installing and monitoring the required data of the solar PV would enable compliance with all applicable aspects of the Standard.
- The energy performance analysis revealed equipment operating out-of-hours, higher setpoint temperatures for VRF systems, systems operating at higher-than-optimal levels of voltage and power factor and uneven load distribution across electrical phases. This analysis informed energy conservation measures based on site audit findings that could be implemented without incurring significant costs.
- The identified energy conservation measures included building optimisation, and lighting and controls upgrades. Implementing these measures achieves a 23% reduction in EUI, meeting operational energy limits based on both floor area metrics, GIA and NIA. The capital costs for installing these measures, along with rooftop solar PV installation, provides payback within 3.2 years.
- A retrofit implementation plan outlined the step-by-step process for implementing measures, including time for solar PV feasibility, planning approvals, energy monitoring, and correcting performance gaps.
Provided the renewable energy recommendations are implemented and the building continues to maintain or better its energy performance, it can meet and verify net zero aligned status by 2030.
Table 1: Summary of the performance of Hamilton House on all applicable aspects of the Standard
Testimonial
”We understand the importance of taking immediate action to lower energy consumption across our properties to achieve high performance standards, bringing value to our occupiers. We regard Greengage as a trusted sustainability expert that shares our commitment to making tangible, measurable progress in decarbonising our portfolio. We are very pleased with the net zero carbon audit undertaken, with their in-depth analysis and insightful suggestions being crucial in identifying decarbonisation opportunities for the building.”
Garith Brown, Senior Asset Manager, Dorrington.
