The Oamaru motel has received a Qualmark Five-Star Gold Sustainable Tourism Business Award.
It is one of just four motels in the country to have received the honour.
Qualmark defines the award as recognition for "the best sustainable tourism businesses in New Zealand, with the delivery of exceptional customer experiences an integral part of everything they do".
Debbie and Ross Ward opened Mariner Suites in 2021 and gained a Five-Star Silver Award in their first Qualmark assessment in 2023.
The couple had been working towards achieving the gold standard since, Mrs Ward said.
She said to maintain the five-star rating Mariner Suites had to consistently "represent best practice" in exterior buildings and gardens, public areas, guest bedrooms, guest bathrooms and services.
The Qualmark assessor was impressed by the motel and the "thought behind its design and architecture".
"The complex has been built to maximise natural sunlight angles with over-spec insulation and high-spec double glazing," the assessment read.
"Huge lengths have been taken to achieve architectural and colour harmony with Oamaru’s adjacent Victorian heritage precinct with the judicious use of lines, height, pigments and Oamaru stone on your one-acre [0.4ha] high-profile site.
"As an Oamaru family, you are very community-minded and support an impressive array of local charities and initiatives, directly and indirectly."
Mrs Ward said the assessment was a "testament to the hard work and passion of our entire team".
They also had four years of carbon data tracked since they opened.
"The calculator indicates we are sequestering 34.23kg of carbon for every $1000 of turnover, down from 35.53 last year, and below average for a commercial accommodator, which we are very proud of."
