How do we tell our stories about the past? The Substation is offering cash prizes of more than $1,000 for the best written and filmed explorations of ideas about heritage, posted on social media.

BIG4ENBLOC: The Substation Insta-Film Competition on Instagram and Utterly Changed: The Substation Writing Competition on Facebook are open to entries until noon on Sept 3.

In both cases, submissions are limited to one account and one post a person.

The contests are part of The Substation's programmes until the end of this year, which look at how and why heritage is a political and emotional topic for the public.

Mr Alan Oei, its artistic director, says Singaporeans are beginning to question "the narrative of progress that requires pragmatic and constant redevelopment".

"We can't keep nondescript buildings of no national value even if we've made memories in these places," he says rhetorically, giving as an example the discontent after the old National Library building in Stamford Road was torn down in 2004.

The Substation's home in Armenian Street is geared to spark discussion of what heritage means to Singaporeans and how the city is shaped by conservation and nostalgia.

The basement sports a new bar, SAD (Substation After Dark), which, over the next few months will host a film screening and panel on conservation; a variety show centred on the iconic kebaya of the Singapore Girl, and similar events.

SAD is also open to hosting artists, academics, curators and others who could use the space for a workshop or performance as well as other events.

The facade sports photographic posters of women in the kebaya of the Singapore Girl (a series titled The Land Of My Heart by photographer John Clang); an outdoor old-school "toilet" (Jamban 1956 by artist Hafiz Osman, who says the structure can be used only for drawing graffiti); and an electric sign spelling out the title of this year's programmes: "Cities change. People die. Everything you know goes away".

The grim words lead to the realisation that heritage should not be defined merely by state and heritage specialists. "All of us have to participate in what, why and how we remember," says Mr Oei.

Hence the contests.

Contestants in Utterly Changed: The Substation Writing Competition must write a creative work in English, from 200 to 2,000 words long, in response to local heritage and what it means to them. All genres and forms are eligible, including narrative prose, creative non-fiction and experimental work.

The piece must be posted publicly on the contestant's Facebook timeline, with specific tags. Contestants stand to win a top prize of $3,000 or second and third prizes of $2,000 and $1,000 each. The contest will be judged by a panel chaired by noted writer Boey Kim Cheng, who has won accolades for non-fiction work about heritage such as Between Stations (2009).

BIG4ENBLOC: The Substation Insta-Film Competition is for short films posted on Instagram, with specific hashtags, in response to four buildings that could be demolished for redevelopment. These are the Pearl Bank Apartments, People's Park Complex, Golden Mile Complex and Golden Mile Tower.

The winner gets $1,500 and an economy-class return flight to Berlin, Dessau or Weimar in Germany. The film-making contest is presented in collaboration with the Singapore Heritage Society and supported by Goethe-Institut Singapore.

The chair of the film jury, Dr Chua Ai Lin, is resident artist at The Substation and executive director of the Singapore Heritage Society. She says the four buildings under threat should be considered in the light of today's conserved shophouses. These are sites of businesses and command high rentals. Yet, a few decades ago, many thought these shophouses should be demolished to give the city a face-lift.

She says: "The value we place on the shophouses now shows us how the value of a place or building changes over time."

• For more details of The Substation's programme and competitions, go to citieschange.sg