This research explores barriers to implementing sustainability measures in existing Central London Office spaces from different a Stakeholder’s perspective. Drawing on insights from the literature, this research identifies limitations of building assessment methods and environmental certification including Green Leases, EPCs and BREEAM In-Use. Data from 30 semi-structured interviews across four Stakeholder groups were utilised to extrapolate findings using both close and open-ended research questions which enabled a focused yet conversational interaction with the interviewee. The data analysis and preliminary findings highlight several themes from a Stakeholders perspective, which have so far been unexplored in literature enabling three objectives to be met. The three objectives focus on barriers to sustainability measures with a specific focus on BREEAM In-Use, value aspects brought about by good workspace design, Smart Building Technology, and its influence on Stakeholder’s communication and finally, difficulties of retrofitting existing office spaces with technology to enhance environmental performance and potential solutions. More attention should be given to mitigate issues associated with the BREEAM In-Use certification, specifically auditor integration which can affect innovation, communication, and costs. The degree of value aspects brought about by good workspace design varies according to specific Stakeholder category, nonetheless, all agree that value is brought about; SBT increases end-user control and of all the Stakeholder relationships, the Landlord & Tenant relationship is most positively impacted by using SBT. Despite the surge in demand for sustainable spaces, uptake of SBT is slow. SBT could be used as a complimentary technology alongside building assessments (such as BREEAM In-use) to ensure higher sustainability output of an existing office space is achieved and not hindered but only if the barriers associated with BREEAM In-Use integration are recognised by policy makers and there is a commitment or strategy in place to incentivise Landlords to retrofit existing spaces with SBT. Landlords’ incentives to uptake SBT.