Shampoo in one parcel, socks in another - for many of us, it's become normal to hear several knocks on the door from a courier during a week.

But all this to-ing and fro-ing has an impact on the climate, and that's something delivery companies are having to address.

Despite a rash of press releases about companies buying electric vans, most parcels still travel the country on fossil-fuelled vehicles, according to Rob Levy of Freightways, which owns NZ Couriers.

Electric vans do not quite have the range or power needed for bigger loads, though he expects that to change in the next few years.

"Sadly at the moment, the big factor is the fossil fuels," he says.

Mark Anderton of retailer The Warehouse says the red sheds have been trialling electric vans for whiteware and other deliveries from Auckland, Hamilton and Tauranga, with similar challenges.

The company is committed to fully electrifying its vans (and has already converted its light fleet) but, like NZ Couriers, is waiting for better charging infrastructure and heavier load capacity.

The Warehouse is trialling electric vans. Photo: Supplied

NZ Couriers has started offering its business customers the option to track the greenhouse gases of deliveries, and Rob says 100 companies from all kinds of industries have taken up the offer.

In the current, mainly fossil-fuelled environment, he says two main factors drive a parcel's planet-heating impact: whether or not it travels by plane, which results in higher emissions, and how many items can be bunched together for the bulk of their journey.

A New Zealand report on decarbonising freight found customers often were not aware of the carbon cost of demanding things quickly, and often were not being charged the full cost of doing so.

Antonia Burbidge from the Sustainable Business Council says businesses were competing in a market that treats speedy deliveries as the norm.

"I'm not sure how conscious that is," she says, adding that people may not be thinking through whether they really need something tomorrow, versus in a few days, versus two weeks from now.

She says, for parcels that can wait, switching cargo from air freight to coastal shipping would be slower, but cheaper and better for the planet.

Her organisation is working on how to make shipping and rail feasible for a bigger proportion of journeys that might otherwise use roads or air.

Some cleaner options are the same speed as fossil-fuelled ones, such as moving trucks from diesel to electric or other fuels, she says.

And for those short city journeys, Antonia says electric vehicles were readily available now.

That is important, because research for the European Commission found the 'last mile' of travel to your house is where most climate pollution happens. It is worse if you are not home, and the parcel has to be redelivered.

Rob says people can reduce the amount of fossil fuels burned by 'bunching up' into single orders, rather than ordering in dribs and drabs.

But that can be tricky when retailers often send items out in multiple deliveries, even if they were ordered at the same time.

Would The Warehouse would consider giving people a click-button option to wait a bit longer and have an order arrive all at once?

Mark does not think it would work.

He says the solution was more about making sure one store has the right stock to fill a person's whole order, rather than having to send items from multiple locations.

He says The Warehouse has used this tactic to cut the number of parcels per order by 25 per cent.

The reality is that customers valued speed, he says, in addition to other factors.

- Eloise Gibson/ RNZ