Here’s why rooftop gardens are good for your health, your house and your wallet

Artist rendering: Baxter Senior Living, a planned senior housing project in East Anchorage, included rooftop greenhouses as part of its initial plans. (Provided by J.R. Wilcox / Baxter Senior Living)

Our vote is yes! The Baxter Senior Living facility will be designed to allow installation of a rooftop greenhouse, according to a recent Daily News article.

This is exciting! While food self-reliance is a major benefit, there are at least two other reasons why this type of development is a good thing for Anchorage.

First, garden roofs potentially result in cost savings in several ways. According to a study by the National Research Council of Canada, normal roof temperatures can exceed 150 degrees on hot days. As the roof heats, air conditioning kicks in to maintain interior comfort level. In cold weather, interior heat seeps out the roof. These extreme hot and cold temperatures cause the roof membrane to dramatically expand and contract, which decreases roof lifespan.

A garden roof helps to maintain a more even temperature inside the building by shading during hot days and insulating during cold days. Eliminating temperature extremes reduces energy needs, allows mechanical equipment to work less, and increases a roof's lifespan. All of this saves money. When spread out over the "asphalt jungle" of a city, it helps to reduce urban heat island effect created by the solar gain amplified from man-made materials like asphalt and concrete.

Additional benefits are a natural filtration of rain run-off as garden roofs slow water movement. Based on a New York Metropolitan Region research report, a garden roof retains over 74 percent of rainfall. A standard roof retains only about 25 percent of rainfall, and the resulting run off allows much more water to flood streets and inundate drainage systems. This extra water weight is why a garden roof needs additional engineering and structural reinforcement.

This technology is not new. Roanoke, Virginia's municipal building has a successful green rooftop. The Chicago City Hall's roof is home for beehives, which help pollinate the green roof plants. Pennsylvania State University has four large-scale buildings: 1. Forest Resources Building, built 2006, with 4,700 feet of extensive roof plantings; 2. Root Cellar, built in 2006 and 2007, with six separate sections totaling 4,500 feet of green roof; 3. Student Health Center, built 2008, with 12,500 feet. of green roof; and 4. Dickinson School of Law Building, built in 2009, with 22,000 feet of green roof. (The last two are not public accessible.)

Next, rooftop gardens and greenhouses have definite health benefits for participants. The AARP offers five primary benefits.

1. Outdoor activity helps increase Vitamin D levels, which benefits bones and the immune system.

2. According to a 2006 Dubbo Study of the Elderly, gardening might also help to lower the onset of dementia by 36 percent.

3. A study in the Netherlands found gardening helped test subjects lower the cortisol (stress hormone) levels in their blood and positively enhanced their mood.

4. Gardening is a great aerobic exercise that helps with stamina, strength and flexibility.

5. Gardening helps to foster a sense of community and accomplishment. Everyone can contribute, no matter what their physical level. Harvesting the nutritional results is a wonderful reward and provides an incentive to continue.

If you doubt the benefits, try wandering through Bell's Nursery during the winter and see how you feel. Did you notice others lingering with their coffee or strolling through the plants? You might not have even realized why you went.

So let's all get excited about the benefits and adapt new building regulations to improve Anchorage's livability and provide green spaces in our urban jungle. Who knows, as the process and designs develop, roof gardens may even become more prevalent on residential homes.