Skip to 0 minutes and 7 secondsA heliostat traditionally is a motorised mirror. And that's about as simple as it needs to be. In the reference of the project, we refer to a heliostat as the whole system. Technically, we would refer to the motorised mirrors on the western tower as heliostats and the cantilever as a secondary array of fixed mirrors. So traditionally, and as product designers, we see the heliostat as a single motorised component. So the primary goal for the cantilever is to deliver sunlight to areas that could not otherwise be achieved with the building design as it is. So we're using a combination of motorised mirrors and fixed mirrors to reflect light to the areas that we determine as a priority area.

Skip to 0 minutes and 51 secondsThe geometry of the site restricts solar access to certain areas. And for the benefit of residents, the purpose of supporting plant life, and just general quality of life of residents in that area, we're trying to introduce the amenity of sunlight in ways that it couldn't otherwise be delivered. So we have a combination of motorised mirrors, which sit atop the west end tower. And they track the sun throughout the day, and they move incrementally throughout the day. They reflect the sunlight up to the cantilever, which is essentially a fixed array of mirrors. And each of the mirrors on that cantilever then has a pre-determined target at ground level or down in atrium level.

Skip to 1 minute and 32 secondsSo the sunlight comes onto the motorised mirrors, up to the cantilever, and then down onto its pre-determined targets. Yann Kersalé was the lighting artist who was engaged to deliver the Sea Mirror, which is what the cantilever projects at a night-time. And so we needed to integrate the hardware for Yann Kersalé into our heliostat system. So there was a combination of technical requirements from both the architect and from the lighting artist that we need to make sure fit well into a single product. A question of how well the system works is a relative one. I think it's very important to understand the key objectives of this.

Skip to 2 minutes and 13 secondsAnd one of the core objectives was to deliver natural sunlight down to the podium level in the shopping centre. And 50% of the mirrors on the cantilever do that very effectively. Without the cantilever system in place, there'd be very little natural sunlight-- and in fact, almost no direct sunlight to that area. So the very centre of the shopping centre is lit naturally by the system. There's also the balance of light which is distributed between the on site leisure areas, like the pool and the jacuzzi, and then also distributed out further into the park.

Skip to 2 minutes and 47 secondsAnd I think the architects and the developers are very happy with what we've delivered and can see the absolute benefit for not just the residents who get to enjoy the sunlight during the day-- which they otherwise would not to be able to enjoy-- but also have a light show at night, which is a very important part of the installation. Sometimes from the western tower, we can look down into the park where the reflected sunshine is, and we can see people gravitate towards those sunny spots. What's valuable about our reflected sunlight is that it's not transient. The sun doesn't move like all other sun.

Skip to 3 minutes and 24 secondsSo people can sit in a sunspot and enjoy that sunspot indefinitely-- or until the sun goes down. Whereas a typical situation in a park, you would sit for an hour and as the sun moves across the tree, you would need to either migrate with it or pick a new spot. The mirrors need to be cleaned regularly to ensure that their performance is as high as possible. We can take a lot of valuable information out of this project. It's the largest architectural installation of heliostats anywhere in the world. And I think we're starting to observe some real benefits that heliostats can deliver.

Skip to 4 minutes and 0 secondsI'd like to think that heliostats can be used in increasing numbers in built-up environments to deliver sunlight to what will otherwise be very shaded and dark spaces. We don't always have to deliver lots of light, we can just deliver a certain amount of light in a controlled way to have a very significant effect. Pubs and clubs, patios, even houses-- we can make a big difference to what people can do with light now and how developers can build as well. We'd like to see that heliostats can improve the amenity of light for many people and give developers the opportunity to build in new and creative ways.

What is the heliostat?

The heliostat at Central Park adds to its unique visual character. Its integration into One Central Park was key to ensuring daylight would be delivered to areas that otherwise would be in shadow.

In this video, Tim Phillips explains what a heliostat is and in particular, how the Central Park heliostat works. Tim is the owner and director of TILT, formally known as Kennovations, an industrial design firm specialised in architectural projects.

Besides the daylighting functionality of the Central Park heliostat, it also incorporates an art piece in the form of the Sea Mirror by Yann Kersalé that operates at night-time. This adds an additional layer to the collaborative design and production of the system, the changes of which will be explored in a subsequent video.

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This video is from the free online course:

Re-Enchanting the City: Designing the Human Habitat

UNSW Sydney