Energy-flexible buildings

This Issue This is a part of the Commercial buildings feature

By - , Build 173

Could New Zealand’s energy-flexible commercial buildings contribute to a low-carbon environment by relieving peak load on the electricity grid? A BRANZ-supported research project sought the answer.

NEW ZEALAND’S ENERGY and electricity system is likely to undergo serious changes with climate change and the decarbonisation of the grid playing a significant role.

Could commercial buildings help manage the electricity grid?

To date, research around flexibly managing the electricity grid using buildings has focused on thermoelectric appliances in the residential sector. Research and quantification of the energy flexibility offered by commercial buildings has been limited.

Despite this, managing the grid using energy-flexible commercial buildings represents an opportunity to achieve meaningful reductions in electricity demand from buildings that are far less numerous than residential buildings.

Research was undertaken to establish whether energy-flexible commercial buildings in New Zealand can maintain the current quality of indoor thermal comfort while sufficiently reducing demand for operators to consider them significant contributors to grid management.

What is an energy-flexible building?

Energy flexibility means the ability for a building to manage its demand and generation according to user needs, grid needs and local climate conditions.

Energy flexibility in commercial buildings could support the integration of more variable renewable energy sources. It could also increase demand response capability – a cost-effective way to manage network constraints and reduce non-renewable electricity generation.

Study simulated energy-flexible operation

The research used case studies of New Zealand commercial buildings represented as building energy models (BEMs) that were simulated under energy-flexible operation in building performance simulation software (EnergyPlus).

The selected case studies were small commercial buildings less than 1,499 m2 that had heat pumps. The building types were office, retail and mixed-use. These buildings were selected due to their significant and sharp morning peaks in electricity demand.

Preheated buildings and relaxed temperature set points

Two simple energy flexibility strategies that aimed to reduce the peakiness of demand were simulated in the buildings. The results from each building were then aggregated and extrapolated across the New Zealand commercial building stock.

The strategies simply shifted heating demand by preheating buildings and shed heating demand by relaxing temperature set points. This was done to test whether implementing simple energy flexibility strategies has the potential to reduce electricity demand by a meaningful magnitude.

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Results encouraging

At best, the commercial building stock’s peak demand could reduce by 177 MW through energy-flexible operation of 45% of the commercial building stock – equivalent to around 11,700 buildings. In this scenario, heating was shifted to start 150 minutes earlier in the morning.

The study concluded that there is energy flexibility potential in New Zealand commercial buildings resulting in demand reductions sufficiently large enough for operators to consider significant for grid management. This could be achieved without seriously jeopardising the current quality of indoor thermal comfort and warrants further investigation into energy-flexible commercial buildings.

Role in decarbonising energy

The reduction could play a role in decarbonising the energy and electricity system by reducing winter morning peak demand and intra-day variability. The reduction in demand could contribute to New Zealand’s demand response capability, which could then substitute the use of gas and diesel peakers.

It could also contribute significantly to Transpower’s demand response capability by doubling it. The reduction in demand could also free up capacity for the electrification of transport.

This finding demonstrates the importance of energy-flexible commercial buildings. Could these buildings play a bigger role in decarbonising New Zealand’s energy and electricity system?

Other opportunities for energy flexibility

Even with a limited set of energy flexibility strategies, energy flexibility could contribute significantly to reducing the commercial building stock’s peak demand. However, the narrow focus on two simple strategies and electric heat pumps leaves many other avenues yet to be explored.

It also opens up questions around what combinations of strategies could be tested to improve the energy flexibility potential of commercial buildings in New Zealand.

Benefits include reduced electricity costs

The results show that commercial building owners or tenants who pay for the electricity costs could benefit from paying less by:

  • shifting demand from peak to off-peak periods where lower tariffs are charged
  • shedding demand during peak periods, therefore paying less.

During the peak period, specifically the peak hour defined in the research as 7–8 am on a winter morning, shifting demand could reduce costs much more than shedding demand, providing greater value to the building owner or tenant.

However, the implication of shifting demand could increase overall electricity consumption and could end up increasing costs. This highlights that there could be value for commercial building owners and tenants by operating energy-flexible buildings to better respond to price signals.

Demand-side solution to support the grid

Overall, the research examined a demand-side solution to support the electricity grid and respond to the anticipated changes in New Zealand’s energy and electricity future. Energy-flexible commercial buildings could respond to those changes and support the transition into a renewable energy and electricity future. 

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Note

Sandi Sirikhanchai is a BRANZ scholarship recipient.

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