Eight ways to make sure your building will perform the way it should
With the advent of NABERSNZ, our local energy-rating tool, there are increasingly fewer places for poor-performing buildings to hide.
When’s the right time to start thinking about energy use in a building? And how can you be sure the building you’re handing over to the client will be a smooth, efficient runner guaranteed to keep tenants happy (and score high on the NABERSNZ scale)?
We recently held a really interesting and thought-provoking session with an owner / developer and team of architects in Auckland. This got us thinking about the various touch-points in the development process and how these can impact on energy use (and tenant comfort) over the whole life of the building.
1. Architects have a lot of influence. More than they realise.
Obviously, one of the biggest energy users in a commercial office building is heating ventilation and air conditioning (HVAC). Although HVAC systems are designed by building services engineers, they’re a direct response to the architect’s design. HVAC size is, in part, determined by the orientation of the building, the facade design, glazing, external shading and materials.
This means it’s important to think from the very beginning about the thermal envelope and aspects such as window to wall ratio. Does it need to be an entire glass box? What about the western side when the sun angle is low in the afternoon, directly heating the space and sending internal temperatures sky-rocketing? How can smart shading maximise daylight while minimising solar gain?
2. The best time to start modeling is when you start design.
Frequently, energy modeling is done when the design has been completed. This is like offering a menu after dinner’s already been served. The real advantage of energy modelling comes when it’s used at the very beginning, throughout design, to help weigh up options and choices. If energy modeling is used to inform intelligent design choices, you’re locking in energy efficiency from the get-go.
3. Don’t just model once – keep it up.
And further to starting energy modeling at the earliest possible stage, keep revisiting it. Going to the gym once won’t get you fit – it’s the same with energy modeling. It’s an iterative process that’s best used to guide good decision-making throughout. Make the energy modeller part of your project team and keep using them.
4. Understand how the client will really use the building.
It’s not uncommon for engineers and architects to write design briefs that are pretty standard and generic without incorporating the client’s unique needs. But how each and every specific space will be used, impacts directly on decisions about energy requirements.
For example, if the fourth and fifth floors are going to be a call centre they’ll need 24/7 heating and cooling. If they’re not on a separate system, the entire building will also get 24/7 heating and cooling by default. Likewise for big server rooms and any central services that can’t be turned off – if any area has special and/or intensive HVAC needs it needs to be on a system that can operate independently, or you’re designing in energy waste. So make sure your services engineer understands exactly what the spaces need.
5. Check your assumptions.
When engineers make assumptions about different spaces within the building these should be explained to the client. It’s easy for information to be lost in design briefs and result in performance of the space not meeting the client’s expectations.
The most energy efficient buildings are designed to take into account hours of operation, staff density, and enable flexibility to suit fluctuations in workforce. Failing to check assumptions about the building can create small and silly errors that become a serious pain – for example, putting a main temperature sensor in a server room. It’s always going to be hot in there - imagine how staff will feel when they’re being cooled to the same level as an energy-hungry machine.
6. Spend time commissioning.
A one-year fine-tuning period may sound like a long time, but it’s necessary, because it enables the system to be checked and assessed in all seasons. Both architects and engineers should be advising clients that it’s worth investing some time in this.
It doesn’t need to be disruptive to the tenant, and it doesn’t mean having an engineer on site all year round – they’ll visit perhaps for 2-3 days every three months to check systems are running as they should. It can even be done over the weekend. Not convinced? Commissioning was what made the difference at the Meridian Building and the NZI Centre
Decide at design stage that there will be 12-months of commissioning and it can be built into the defects and liability period. It also needs to be done thoroughly – you’ll only discover that you have a rogue thermostat wired the wrong way if you physically walk around and test each one. (Hairdryers are useful for this.)
7. But make sure your system can be commissioned in the first place.
It’s all very well to talk about a 12 month fine-tuning or commissioning period, but what do you do if you physically can’t commission the building? It’s surprisingly easy to design a mechanical system that there’s no way to commission.
If you can’t access the relevant ductwork – i.e. you can’t get into the ceiling space – your engineering team won’t be able to do much about those damper that aren’t doing what they should with the airflow. And then you could find yourself in the bizarre and unenviable position of trying to pull a piece of string through the HVAC grille to adjust dampers (don’t laugh, it happens…)
8. Get the client on board.
The last point is the most fundamental. Architects are usually the main point of contact with the client so they’re pivotal in helping clients understand the how’s and why’s of ensuring good energy performance.
This covers everything from talking through energy modeling reports, helping them understand the benefits of a 12-month tuning period, to understanding how user-dependent variables – such as operating internal or external shading - can affect performance.
Make energy part of every conversation. Help them realise it’s not just a technical exercise in making something run better – better performance means a higher value asset, happier tenants, better staff satisfaction, lower operating costs, less complaints and less maintenance requirements. Who could argue with that?