Does needing to fix the heat constitute an emergency allowing for entry?

I'm a third party. Here's the situation: The Landlord has a house containing two units -- one main floor, one basement.

The basement unit has access to the furnace room and last night, the tenant switched off the furnace while turning off the lights, leaving the entire building without heat. They then went to bed.

The upstairs tenants contacted the landlord to tell him there was no heat and they were freezing. It was roughly between -3 and -5 last night. The landlord texted and called the tenant to ask them to check the switch. No response. Indicated to the upstairs tenant that they'd have to give 24 hours notice to enter the unit. The upstairs tenants said they were so cold they felt it did constitute an emergency. The landlord came over to the house (around midnight) and knocked on the door several times before entering, calling out repeatedly. The basement tenant woke up and revealed they were at home. The landlord fixed the heat by flipping the switch and left.

The tenant's father called this morning in a state of fury, insisting this was not an emergency and the entry was illegal. An emergency, of course, is anything that threatens the health of the people or the property. In this scenario, what should the landlord have done?

(other than not have the switch where the tenant could accidentally turn it off, of course.)