Paul and Patricia Grogan, both 81, built an energy-efficient passive solar home near Dublin in the 1970s.After almost 50 years, they're listing the 4-bedroom property for $1.32 million."There'll be a lot of tears when we leave this place," Paul said.It was the early '70s, and Paul and Patricia Grogan were looking for a new home.The couple, who met in college in the '60s, lived in a cozy family house in an outer suburb of Dublin back then but dreamed of building one on their own."We suddenly thought we'd love to maybe strike out and be a bit adventurous. So we started looking for sites," Patricia, 81, a former teacher and retired special needs assistant, told Business Insider. Paul and Patricia Grogan built a passive solar house in Ireland in the '70s. Paul Grogan. They stumbled upon a stunning plot in Kilcroney, a small town about 30 minutes outside Dublin. It was slightly over an acre, with a stream running through it, and offered views of a small mountain nearby."It was a forest and there were grass and trees and weeds growing up to it. You couldn't get into it actually," Patricia said. "But it was a beautiful spot."The couple knew that they had found the perfect place to settle down. But before any construction could take place, the couple had to clear the site."We spent many happy picnics with friends out here clearing the site," she said. "And we had to take out a few trees in order to have room to build the house."Building an energy-efficient houseLiving in Ireland, where the skies are often cloudy, they wanted their house to let in as much natural light as possible. They also wanted to be able to enjoy the views of the surrounding natural landscape. The glass front meant that their house was able to absorb and retain heat. Provided by Colliers Dublin / Luxury Portfolio Their architect helped them design the"I suppose we liked the idea of being able to see things out of the house just like our previous house," Paul, 81, who does consulting work for the design and maintenance of database systems, told BI, "There was glass all around the courtyard, where we had a little garden with bamboo growing in it."The glass front turned their house into a passive solar home, which meant that it could collect and retain heat from the sun to warm its interiors, thereby reducing their energy consumption, he said. While there is a lot of interest in sustainability now, Paul said it was "unusual" at the time to think about houses in that way. Provided by Colliers Dublin / Luxury Portfolio Be it earthen homes that keep cool in the summer or resilient towns that can survive a category-four hurricane, there has been a growing interest in sustainable houses in the face of rising temperatures and the climate crisis.But in 1976, the year they built their house, it wasn't common to think about houses that way, Paul said."It was unusual at the time to have such a system, and it works pretty well. We do have to provide supplementary heat on very cold, wet days, though," he said, adding that they have a few radiators and a wood fire stove on the first floor.During the summer, when the temperatures are slightly higher, the couple opens all the sliding doors on the glass front of the house, he said.It's the only house in their neighborhood that's designed this way, he said.Paul added the house has a building energy rating of C1 which is on par with houses built in the country since the year 2000. In comparison, most houses in Ireland built before the 1980s typically achieve a low D or E in terms of energy ratings."So heating costs would be lower than most of the Irish housing stock," he said. The glass front of the house comprises windows and sliding doors that can be opened during the summer. Provided by Colliers Dublin / Luxury Portfolio It helps that the property is surrounded by trees that offer some shade during sunny days."If we feel the heat is getting too much, we can open the windows upstairs and get a draft down through that," he said.It took less than eight months for their house to be built, Patricia said.Their friends came out to help them with tasks like painting the beams, she said: "We've done nothing to them since. They've just got a nice mellow color now."The couple says they spent about 35,000 Irish pounds to build the house back then. The Irish pound was replaced by the euro in January 1999. It took less than eight months for the house to be built. Provided by Colliers Dublin / Luxury Portfolio "It wasn't a very expensive house to build. We were surprised, but that's because of probably the simplicity of the construction and the bit of work we all put in to help keep the cost down," Paul said. "But that was 1976, and things were cheaper then, too."A home filled with beautiful memoriesWhen they bought the plot of land, the couple had three kids, but by the time they moved into the house, they had four."We got a surprise pregnancy, and it was quite stressful at the time, but we did it," Patricia said.Every nook and cranny of the house is filled with beautiful memories, Paul said."It's been a very happy house for bringing up the children. They all loved the fact that there's plenty of wildlife around here and in the forest," he said. They've raised their four daughters in the home. Provided by Colliers Dublin / Luxury Portfolio They've kept dogs, cats, and hens throughout the years. At one point in time, they even had ponies, too, Patricia said.Her favorite spot in the house is her office on the second floor."Somebody came out here recently and said, 'I don't know how you managed to do any work here. Just looking out in the garden is lovely," she said.Paul's favorite spot in the house is the kitchen because "that's where everybody congregates." It overlooks the garden, and it's where they've had many "wonderful parties," he said. Patricia's office on the second floor overlooks the garden. Provided by Colliers Dublin / Luxury Portfolio When the couple first moved in, there were only two or three neighbors. But over the years, the community has expanded to include about 17 houses, each on about an acre or more of land, Paul said."And we're all in the same WhatsApp group. So if anything happens in the area, everybody's on," he said.There's a walking trail that runs along the area and into the forest that the couple and a few neighbors have cultivated and maintained over the years. The neighborhood is a close-knit community where everyone looks out for each other. Provided by Colliers Dublin / Luxury Portfolio "We encourage all the neighbors or their children to walk around the area, which means we all meet one another fairly regularly as they're passing by," Paul said.It's a close-knit community where everyone looks out for each other."In fact, we have a long drive it's about 500 meters from the house down to the road. When we leave our bins out, we have to bring them down to the end of the drive. But our next-door neighbors, when they're going for a walk, they'll pick up our bins and bring them up to the house," he said.Plans to downsizeAt the moment, only the two of them live in the house; their four daughters are all grown up, and three of them live in London. The couple's four daughters have since moved out of the house. Provided by Colliers Dublin / Luxury Portfolio "We've grown into it. We've taken over, we've spread ourselves out," Patricia said.However, maintaining a house and garden of this size takes a lot of work. As they're getting older, they've decided to list the house on the market for 1.275 million euros, or about $1.32 million."I spent a lot of time in the garden, which I really loved. But I'm just coming to the point now where I'd like to do some other things in my life besides gardening," Patricia said, with a laugh.Their plan is to move into a smaller place closer to Dublin, where it's easier to get around."We both still drive but would like to use more public transport, which is free for pensioners in Ireland," Paul saidThey'll be sad to leave their neighbors, he added. They're planning to sell the property because they're getting on in age. Provided by Colliers Dublin / Luxury Portfolio While their eldest daughter considered buying the house a few years ago, Patricia says she knows the house requires "a big commitment."The property is about 40 minutes from the Dublin airport and about 15 minutes from the coast, making it a great place to live, especially for those who can work from home like he does, he added.In fact, working from home was a major factor in his decision to continue working beyond the normal retirement age."I love my work, the mental challenges it presents, and the ongoing relationships with my clients," Paul said. "I may slow down a little, but love the stimulus of problem-solving and ongoing study of new technology my work provides." An ideal buyer would be someone who would enjoy the views and the challenge of taking care of the house and its garden. Provided by Colliers Dublin / Luxury Portfolio "The trees, we think, have kept the place, the air, and us very, very healthy," Patricia said. "We feel the trees have looked after us, and they're very big now, but definitely they've looked after us."In many ways, it's been a home that has grown with them."We were excited at the beginning about just doing something very different, but it's been a very happy place for the family," Paul said.One thing's for sure, Paul said: "There'll be a lot of tears when we leave this place."