Making buildings as energy efficient as possible

Being truly net zero is about slashing emissions before looking to other measures

One of the key principles behind a net zero carbon building is ensuring you explore all options to reduce operational energy before you consider any offsetting options.

This is done by seeking out energy optimization solutions suited to your assets. This can often be an intricate process because every building is designed differently, and all tenants will have differing levels of ambition around Net Zero Carbon (NZC).

Even so, increasing interest in net zero carbon is now driving conversations between landlords and tenants. And questions around the role that energy optimization plays in the NZC framework, the NZC benchmarks available and the process for optimizing building operations to align with NZC principles frequently arise.

What role does energy optimization play in achieving NZC?

For an asset to truly achieve NZC in its operations, it can’t just offset all of its emissions; it has to have followed a hierarchy of actions. The first step is to ensure the building is running as efficiently as possible, optimizing building services and usage. Only then should you look to both onsite and offsite renewable energy before determining how many emissions remain that cannot be removed and therefore need to be offset.

But ensuring buildings are running efficiently isn’t as simple as a one-time audit and making some changes to a BMS. It needs to be managed on an ongoing basis to really optimize the operational energy performance.

What benchmarks are available for determining the optimum energy usage of a building?

For most standing buildings, there are considerations that limit the extent to which energy optimization measures can be undertaken, including the building type, finances, geographical location, hours of occupancy, and tenant lease agreements.

It is therefore not possible to achieve a net zero building by simply optimizing the building operations. Nevertheless, targets and benchmarks can help provide guidance on the best practice approach towards minimizing carbon impact. These include:

  • The Carbon Risk Real Estate Monitor (CRREM) which modelled their targets aligned with both climate change scenarios of a 1.5- and 2-degree Celsius increase in global temperatures. Their model indicates that an office should aim for an energy intensity of 25.1 kWh/m2/yr by 2050 to align with the 1.5-degree temperature increase
  • The Royal Institute for British Architects (RIBA) 2030 Climate Challenge sets a target of <35 kWh/m2/year for domestic buildings and <55 kWh/m2/year for non-domestic buildings
  • The London Energy Transformation Initiative (LETI) sets the same targets as RIBA for domestic buildings and non-domestic (specifically office) buildings
  • Other initiatives, including those provided by NABERS and CIBSE, are less prescriptive in asset type targets. Nevertheless, they provide useful guidance and, especially in the case of NABERS, are gaining increasing adoption 

The aim of the energy optimization step in the hierarchy is to increase the energy efficiency of the building as much as possible, ideally working towards achieving these targets and benchmarks. Reducing energy demand will mean that renewable sources of power can increase their share of grid supply much more quickly, achieving carbon reduction benefits for everyone.

How can building operations be optimized?

Optimization should start as soon as the building is practically completed. All centralized plants need to be commissioned once the building is occupied to ensure that design intent is aligned with operational needs. This is also important when there’s a change of tenancy and occupants undertake fit-out works. Often spatial requirements cause internal changes that do not align with the operation of the central plant which can lead to challenges with keeping conditions comfortable for occupants. Monitoring your conditions provides good opportunities to optimize energy which could help improve tenant satisfaction.

You should also consider enhancing and upgrading the existing controls and monitoring systems alongside an intelligent analytics platform that will to provide proactive monitoring and detection of operational issues. A proactive fault monitoring and diagnostic system should be fully integrated with planned and preventive maintenance to reduce equipment downtime and maintenance costs.

However, most optimization and carbon savings opportunities will result from remedial works to parts of the centralized plant that are not operating as designed and where control parameters are creeping out of sync with the building usage. Different assets will require different interventions.

How does a building’s age affect energy optimization?

Where a building sits in the asset lifecycle will determine the level of ambition and investment available towards optimizing its energy performance. For example, for a building with an installed plant nearing its end of life, it’s more economical to ensure good housekeeping and maintenance for continuity of service.

In such cases, forward planning for a replacement is the best investment to ensure that a systems solution which is aligned with future aspirations of the building and which meets the requirements of the building’s occupants is put in place. 

Similarly, for a building with a plant well within its serviceable lifetime, you could consider retrofit and optimization options that pay back within the remaining lifespan of the plant. By opting for an energy optimization system, you can typically achieve a 10 to 20 percent saving during the first year of implementation. Continued monitoring thereafter will allow the energy performance to be maintained at the optimum level.

The additional installation of advanced control and monitoring technologies, for example wireless indoor environmental quality sensors, can support the future evolution of the asset to finetune operations dynamically rather than retrospectively. Such technologies can contribute towards meeting ambitious targets like LETI while supporting improved comfort, health and wellbeing for occupiers and helping portfolios to move closer to net zero carbon. 

This article is part of our Net Zero: The Big Questions series which looks at some the complex questions around how buildings can achieve net zero carbon. Check out the rest of the series below:

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