"We understand this is related closely to consumers increasingly recognising the benefit of smart TVs", Chris Wilkinson of First Retail Group said.
"[Consumers want] to benefit from platforms such as Netflix ... as they become familiar and confident with alternative entertainment options.
"Accessibility to this technology is also a factor as the cost of new appliances remains relatively affordable."
Escalated sales over the 2013 to 2014 period ran parallel to the move towards digital television, Retail NZ chief executive Greg Harford said.
Meanwhile, sale numbers were lowest in 2016 when just 312,354 were sold - likely due to consumers not buying new televisions each year.
"The improved technology and relative reductions in prices will see many people now starting [to] think about buying new sets," Harford said.
"There would have been significant sales in 2014 as people moved to replace secondary televisions with new flatscreens; and as people took advantage of great prices to buy second sets."
As consumers continued to separate from subscription platforms, such as Sky, Wilkinson expected television sales to continue upwards.
A government agency, ECCA was responsible for working to improve the energy efficiency of New Zealand homes and businesses.
The authority's sales data was collected after assuming energy consumption reached an average of 10 hours of usage per day.
The average was sales-weighted, meaning it depended on the energy efficiency of units that were actually sold.
Energy star ratings helped consumers easily compare the efficiency of similar products, however, limitations of the sales data could be experienced because rating calculations were inconsistent across different years.
