“Light has a subconscious impact,” says David Justice. “It can affect your mood. It can affect your sleep. It can affect your appetite. It can make you feel safe.”

David Justice is managing director of Ambience Lighting. Behind the company’s spartan showroom façade in Fairfield there’s a new laboratory under construction. It’s littered with prototypes and works-in-progress. When its new lab is finished, David boasts, it will be able to simulate the exact light level, distribution and colour on a particular bottle of hand moisturiser. That’ll be particularly exciting for key client Mecca Cosmetica.

The most eye-catching thing in the lab at the moment is a chandelier made from a rainbow of Posca paint pens, which will feature in a new cafe in Collingwood. “You really need to have individual data for every single globe and fitting,” says David’s brother Stephen, the company’s marketing manager, as he switches on the Posca chandelier. It’s quirky without being twee, colourful but not overbearing. They’re looking at entering this piece for a design award.

Ambience was started by their father in the 1980s, and since they’ve taken it over they’ve gradually shifted it from being a company selling lights to being experts on how lighting affects people on a deeper level in dozens of contexts.

“If you go somewhere with bad lighting, you know about it straight away,” says Stephen. It feels wrong. That’s what the lab is for. We can test the conditions of anything.”

“That sort of technical knowledge is dying,” he says. And he and David consider it their business to keep it alive.

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Ambience is currently navigating the council red tape around lighting AC/DC Lane. It has lit clothing stores, yoga studios and churches. It lit The Commons, the eco-friendly apartment block in Brunswick. It has taken on jobs with budgets from $300 to $10,000. Ambience goes anywhere atmosphere matters.

The Broadsheet Restaurant, for instance.

“For the Broadsheet space, we needed to let people focus on not just the food, but the furniture, the crockery, the art on the walls,” says David. “People are going to be there for quite a while, eating a meal, and we have to control how people feel in that environment.”

Atmosphere is considered in hospitality environments of all stripes. You expect, for example, for a fine-dining experience to feel right. Glare has to be kept at a minimum. Colour temperatures are kept between 2700–3000 kelvin, a warm, golden colour that makes diners feel healthy and relaxed. In Ripponlea’s Attica (another of Ambience’s projects), diners dwell for a few hours. The minimalist work of architects Russell & George features well-lit white tablecloths offset against dark-grey walls. “The food is the hero,” says David, “so the lighting has to reflect that.”

At the other end of the spectrum, Ambience handle Grill’d restaurants, which subverts its chain burger joint origins with distinctive spaces such as its Flinders Lane branch, where cardboard tubes descend from the ceiling like organ pipes. “If you didn’t know it was a Grill’d you’d just see a beautiful architectural fit-out,” says Stephen. But it’s still a casual environment, so the lighting has to be friendly, unobtrusive and versatile, while still enhancing the work of the architect.

“If the lighting goes unnoticed,” says David, “then we’ve done our job.”

David and Stephen have been doing the practical stuff with the company since they were in school. It was a more straightforward operation back then, supplying lighting to businesses and private homes.

By the time their father was ready to retire, David was ready to take over. Now, he and his brother have developed a reputation for looking deeper at something that most people take for granted.

Take the Toorak branch of Mecca Cosmetica. The Justice brothers developed frosted horizontal lights for either side of the store’s mirrors, which with a controller, can can simulate the light conditions of a sunny day, a night-time interior, an office or a smartphone camera. “Basically day mode, bar mode and selfie mode,” says Stephen.

“Unless a room is lit properly,” Stephen says, “you’re not doing it justice.”