Almost 40pc of consumers believe their financial situation has worsened in the past year, according to new research commissioned by the retail giant.
The research, conducted by Amárach Research, found a quarter of those surveyed believe their finances will continue to get worse this year despite a moderation in the rate of inflation.
A total of 86pc of the 1,200 respondents said they had taken steps to manage their energy bills.
This desire to save money on heating was reflected in sales in recent months, the retailer said.
Purchases of the retailer’s velvet fleece-lined leggings soared by 39pc from mid-September to mid-January.
This equates to around six pairs of leggings sold every minute in Ireland during this time.
Penneys introduced similar leggings for children, as well as long johns for men, which contributed to the rise in sales in recent months.
Its fleece jumpers for women also recorded a surge in sales, with 80 sold every hour between mid-September and mid-January.
“Weather and retail are so closely linked,” Fintan Costello, head of Penneys Ireland and Northern Ireland, said.
“We had two weeks of particularly cold weather and we saw great uplift in knitwear, hats, scarves, gloves, knitted accessories, so you can see that spike.”
As well as reducing their energy costs, 71pc of adults now eat out or order takeaway less often.
While 47pc opted to cancel an entertainment subscription.
Around 62pc said that they switched to a more affordable grocer to save money.
Penneys is set to open a new outlet in Bray, Co Wicklow, this year, with planning permission also granted for a €60m expansion of the Cork city store.
High energy costs are also triggering changes for the business itself, with the introduction of LED lighting contributing to savings of up to 30pc on bills.
The retailer, which sources a volume of goods in Asia for the European market, said it has not been significantly impacted by the Red Sea shipping crisis, bar higher shipping times.
Mr Costello said: “All shipping is now going around the Cape of Good Hope, so there is a 10- to 14-day delay but we have fantastic stock management levels in our business.
“You certainly won’t be seeing shelves running out of anything.”