First eco-friendly greenroof project on Bali incorporating water retention, recycling and conservation methods -
By Victor Sinclair
Situated in the hills behind Lovina, North Bali, the region is notorious for the scarcity of its water in the dry season. Two factors are the driving force behind the design of Villa Santai (santai = relax): conservation of energy and water resources. Projects to introduce changes in the usage of energy, water resources and waste management, etc. are dependent on private initiatives.
The concept was to build an environmentally friendly villa reducing the need for electricity using green lawn roofs that conserve and retain water. The villa is specifically designed for people who are aware of the global climate crisis and are willing to set examples for environmentally friendly building concepts.
The land, approximately 3.600 m2, was chosen for two main reasons, firstly it borders 70 meters on a river - although in the dry season it carries no water, in the wet season it is a source of abundant water - and secondly, is just far enough from the main road to insure peace and quiet.
An application was made to the land department for permission to build on the plot because of its 50° gradient. The plot was terraced into 14 separate levels leading down to the banks of the river, with an even steeper gradient of 80° with a depth of approximately 10 meters.
The application was granted and the earth was “redistributed” into four main levels. The steep bank of the river was “reshaped” to incorporate a Water Recycling Biotope of approximately 50 meters in length and 2-5 meters wide to process 85 m3 of water.
The riverbed and the banks on either side were “sleeved” to a depth of 3.0 meters and a width of 3.5 meters. Both ends of the river were then dammed, resulting in approximately 420 m3 of retained water. Together we then had water catchments totaling 525 m3.
The actual villa buildings are designed with pitched greenroofs totaling 615 m2 of grass at angles of 35° and these are the green lungs of the villa complex. Designed around the theme of water, the villa complex is divided into three separate buildings, and four distinct levels.
A wooden roof construction to support an organic greenroof in the tropics is not an option because of all the insects that just love to feast on wood. Wood can be treated to avoid being eaten; this then becomes a question of environmentally friendly chemicals. The only real option was to use poured re-enforced concrete.
Not only was the idea of pouring a pitched concrete roof something unheard of by the local population and our construction workers, but piling earth on top of it and planting grass was enough to cause laughter and ridicule, at the mere mention of it! Unfortunately the reaction of many expatriates was not that different when they heard of my project.
All this only re-enforced my determination to continue and to prove that greenroofs were not only energy saving, but would enhance the overall picture of a new villa in the landscape and have positive effects for our environment.
30 men and women were actually necessary on the roofs to do the pouring. With the pitch of the roof and the human bucket chains crawling over them, the work was tedious but successful, the resulting photos having historical as well as sentimental value.
The pitched greenroofs are also an integral part of the rainwater retention system. Not only is the rainwater that flows off the greenroofs retained in three separate retaining tanks that are hidden under the terrace surround of the Lap Pool - retaining 200 m3 of water - they also supply the water the greenroofs need to survive the dry season.
When the rainy season began again, the few leaks that appeared were taken care of and the roof was treated with water sealant cement. Finally the question that was on everybody’s mind, “How to get the earth or substrate to ‘stick’ to the pitched roof?”, was answered: grass.
The decision of what grass to use was not easy; there are many grasses that can be used, short rooted, not too thirsty etc, but in the end the classic slow growing golf course lawn seemed the best bet.
The day came when the grass finally arrived. For two days ‘human chains’ had put all the substrate on the roofs and lawn squares were ready to be placed - then the rains came pouring down. The roofs were covered with tarpaulin to stop the earth running away while the grass squares were put in place.
The weather forecast told us rain for three days, the decision was made to continue, but when sections occasionally took off and hit the deck, skepticism about the success of project greenroof was rekindled. On the third day the grass lawn was up at last and as a sign of welcome, the sun came out.
The result? Astonished compliments and amazement at the real cooling effect under the greenroofs, naturally some still thought that with all the rains the greenroof would go swimming. The greenroof ‘skin’ has held.
The leading architect for greenroofs in the 1960’s – 80’s, Friedenreich Hundertwasser, said;
“The nature that we have on the roof is that piece of nature that we murdered, when we put the house there.”
Climate crisis; it is possible to discuss, debate and procrastinate, but if every building gave back on its roof the nature it took, the crisis could be managed and would not be an impending disaster. For Bali and for Indonesia it would be fantastic if greenroofs become a trend.
Pictures, general information and further details:
balivilladesigner.com
