top of page

LEED for Existing Buildings Operations & Maintenance (O+M): Plaza33 Case Study

Green certified buildings are often subject to speculation of “greenwashing” when building users and facility managers realize that the building possesses a certificate that means little or nothing to them. Typical complaints are observed from occupiers of certified green buildings such as “our space is too cold (or too hot)”, “the lights are always on”, “the motion sensors are not functioning” or simply “I don’t know what is green about this building”.

Why is this?

Most green building rating systems for newly constructed buildings use a checklist system that allows a building to achieve certification by opting for specific “credits” that are feasible at the project design and construction phase. These credits are then awarded on the basis of compliance through evidence of as-built drawings, signed declaration letters and design simulation reports i.e energy, daylight or CFD (Computerized Fluid Dynamics) modelling reports that should closest resemble actual building performance. While these evidence do reflect the building’s green features as it has been designed for, it does not necessarily reflect the performance of the building say, a year or 5 after it has been occupied.

Verification and continual optimization of systems, operational staff training and awareness, and occupants’ uptake and satisfaction feedback mechanism are some key elements in the operations of a green building that is not always captured in the design and construction certification stages.

This is where the significance of a LEED for Operational + Maintenance (O+M) for Existing Buildings certificate comes in. A LEED O+M certification provides the tools and guidelines necessary to maintain the reputation and status of a LEED certified green building through assessment of actual building performance data and occupant feedback.

To assess the performance of the building across various categories of a green building certification, the LEED O+M v4.1 scores a building performance through the Arc platform performance scoring system. A performance score is a weighted composite of five performance categories including energy, water, waste, transportation, and human experience[1]. Each of the assessment categories contain credits that require actual building performance measurements such as annual energy consumption, potable water use, occupant feedback, IAQ Audit test results, transport usage data and waste generation.

Data gathered from the building is then uploaded to the Arc platform where the metrics are normalized and compared to a baseline of data from 3,103 projects around the World[1].

In May 2022, we achieved our first LEED O+M for Existing Building v4.1 Certification for an office tower. The Green RE design + construction stage certified office towers of Plaza33, located in Jalan Semangat, Petaling Jaya is the first existing building to be certified under the LEED O+M v4.1 rating system in Malaysia and is a great case study on the topic of “continuity of green building performance and optimization”.

When undergoing process for certification, Plaza33 was required to conduct an ASHRAE Level 1 energy audit by an independent third-party auditor as a pre-requisite for certification. The purpose of the audit was to ensure energy-efficient operating strategies are maintained, energy conservation measures are recommended and goals for further improvements are set in place. This is done through analysis of actual annual building energy and water data over a course of 3-5 years (to account for covid-lockdown related reading inaccuracies), site audit to check on systems operations and conversations with the FM team to understand operational strategies.

Such audits and surveys reduce the gap between what was designed and how a building operates and provides a foundation for employee training and improved systems analysis, and a pathway to better occupant satisfaction.

The process of certification for Plaza33 from appointment of consultants till final certification only took 7 months. In a nutshell, the following efforts needed to be in place prior to certification to secure sufficient points for a Gold rating:

  1. ASHRAE Level 1 Energy Audit by independent third party auditor

  2. Analysis of water consumption and water fitting flow rates

  3. Upgrading the capacity of the Fresh Air fans in spaces to ensure that ventilation in occupied spaces meets the minimum recommended in ASHRAE standard 62.1 Ventilation for Acceptable Indoor Air Quality

  4. Conduct an IAQ Test to determine levels of TVOC and Formaldehyde in occupied spaces

  5. Conduct a transport survey to determine uptake of alternative modes of transportation such as bus, train, walking and cycling.

  6. Assessment of site management practices and upgrade to use of only organic fertilizers and electric or manually powered equipment

  7. Purchase and implementation of an on-site waste composting system

  8. Set in place a waste management plan, implement it and conduct a waste audit to determine volume of waste that is being successfully diverted from the landfill

  9. Implement an integrated pest management system to reduce the use of pesticides and take into consideration occupants health when applying pesticides on-site.

Upon establishment of the above efforts, Plaza33 was able to achieve a high-performance score of 74, which is higher than the global average of 69 and higher than a national average of 70. Breakdown for each category is shown in the graphic below.

Plaza33 Performance Score based on actual energy and water consumption input, survey and audit results.

In summary, while LEED certification for new buildings is an important tool that provides a clear guideline for new projects with sustainable goals, the journey toward low carbon emitting buildings with spaces providing good indoor air quality does not end there. It is an ongoing journey that requires active involvement from the tenants and especially facilities management teams of the building to consistently improve and optimize the building's performance, this is most easily done through the LEED O&M certification and recertification process.

Let us know your thoughts and comment on our LinkedIn


  1. Performance Score Arc Skoru (

  2. Carbon Footprint Elmina (


bottom of page