Gareth Ryan (MCIAT) is a Member of the Chartered Institute of Architectural Technologists. Contact him at 023 8821807 or 087 7444568.
The architectural principle around the use of shelter and screening have a number of characteristics, which affect the design of a house on a site or extension/renovation of a house. The prevailing wind in Ireland is south westerly, which affects the protection of a house in its exposure to the natural environment. Trees, walls and planting can all play a part in minimising the effect of this on a house. Shelter and screening also have a number of different influences on the immediate environment of a house with both the solar gain within a house and privacy for the occupants of a property being impacted.
The prevailing wind being from a south westerly direction would naturally suggest that one should erect trees, walls and planting in this orientated direction from the house. Similar to the principles examined in the last column in this series there are varying abilities to control its impact on a house within the rural or urban settings. Trees have significant benefit for sheltering a house from the wind but, which maybe easier to plant in a rural context, as if they are planted too close to a house they negatively impact on the solar gain, which can be achieved in a house by shading it from the sun. The recommended distance for planting a tree away from a house would be between 60m and 20m for a 15m high tree and for it not to have a negative impact on the mid-range angle of the sun in Ireland during the year. There is also a difference in the advantages for solar gain in a dwelling depending on whether one uses deciduous or conifer trees with the former allowing sun light through the branches when they loose their leaves in the winter and the sun is at a lower angle in the sky. The inclusion of the impact of trees on a dwelling is not always a major concern for those working on the design of a house or renovation/extension of a house especially those in the urban context as the buildings there can have their own constructed screening and shelters by other buildings and walls. In the rural context it should be considered in the design as it will impact the enjoyment of living in a house and within the curtilage of a house.
What can be more of a concern in towns or cities is the element of privacy, which can be achieved by using shelter and screening such as walls and hedgerows. As referred to in the last column of this series hedgerow planting and walls can be used to great advantage to allow for the proper orientation of a house and the rooms within it. Hedgerows in comparison to the length of time that one is going to live in a house do not take long to grow and can be more pleasant on the public side of a house than a block wall and will provide enough privacy with the right selection of plants which can grow to the appropriate height. The orientation of living spaces is more important in my opinion as one cannot change the direction or angle of sunlight reaching the earth while one is easily able to grow plants or build a wall.
I sight my grandparents farm house in its vernacular architectural style again as an example of both using horticultural and man-made features in the manner described above. At this house there are trees planted between 20m and 30m in a south westerly direction away and in line with both the south and west walls of the house in the exact direction of the prevailing wind and which therefore provide shelter for the house and its occupants. The house has also got a lovely feature of an external room with a wall at approximately 4m from the southern face of the house running parallel to the house, approximately 1.1m high, with a gate at both ends which provides a perfect external enclosed courtyard space for external family activities. The builders of this house may have had a couple of other considerations when building this external room as the level of the ground is lower outside of it but it provides a perfect private space which although not in an urban context separates the farm from the dwelling for privacy.
The next column in this series will follow on from the reference to the shadow created by trees and other buildings around a house, affecting the solar gain in the house, by looking at different types and sizes of windows or doors and the affect the direction in which they are orientated on the building has on their selection.