The Constructor

How to Plan a Building Site for Solar Access?

how to plan a building site for solar access

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Planning a building site for solar access is essential for implementing a successful passive solar design. The objective is to make sure a building has good unobstructed access to the sun during the winter season. 

The importance of site planning for maximum possible solar access is an ever increasing demand. This is manifested through specifications set to ensure good solar access for newly constructed buildings.

For example, the United States Green Building Council (USGBC) developed a LEED for Neighborhood Development (LEED-ND) program, which is a great step towards broader consideration for solar access.

Why is Solar Access Important?

  1. It is a crucial component of passive solar design.
  2. The property's design might get rejected by local authorities if it overshadows neighboring buildings without a plausible reason. For instance, a building should allow a minimum of two hours of solar access to neighboring property, as per guidelines in Victoria/ Australia. And a minimum of three hours in New South Wales should be strictly followed while a building is designed.

How to Plan a Site for Solar Access?

The objective of site planning for solar access is to permit the south side of the building to be exposed to as much sun as possible during the winter months.

The glazing of a building should be within 60 degrees of either side of the true south to get enough heat energy. This can be achieved by limiting the distance between a building and its fences and neighboring buildings.

Figure-1 illustrates the required distances for a building located in Minot/ South Dakota/ US. Unfortunately, the space required for optimum solar access shown in Figure-1 is not always available. Therefore, shading patterns in smaller areas should be assessed carefully to reach the best possible compromise.

Figure-1: Ideal Solar Access for a Building

Planning for solar access at the largest scale can substantially simplify the design for natural light at the building scale.

Provision of solar access is easy when streets run within 25 degrees east-west because building footprints are either face or back up to the south, see Figure-2.  If streets run north-south, the creation of cul-de-sac ensures solar access for buildings of a subdivision, see Figure-3.

Figure-2: Solar Subdivision Layout (Solar Access can be Provided to the Back Yard, the Side Yard or the Front Yard of Solar Homes)
Figure-3: Solar Subdivision Layout (Short East-west Cul-de-sacs Connected into North-south Collectors is a Good Street Pattern for Solar Access)

If buildings are located on a sloped area, the distance between individual houses should be considered for solar access. For example, figure-4 illustrates the distance between single-story and two-story buildings on a sloped site.

Figure-4: Effect of Sloped Area on the Minimum Distances between Buildings to Provide Solar Access

The impact of trees on solar access should also be studied as it is possible that energy-saving from the tree's shade during the summer months may outweigh energy-saving due to the maximum solar access. 

Trees should be of a suitable type and positioned correctly on the property boundary. In addition, the mature tree height, shape, location, leaf-out and leaf-drop properties, and winter bare-branched shading should all be considered for solar access.

Advantages of Solar Access

  1. Improve the energy efficiency of buildings at almost no additional costs.
  2. If combined with other sustainable building techniques, it significantly reduces energy consumption. For example, a building with its long face on the east-west axis and a large percentage of its windows on the south side consumes 25% less fuel.
  3. Placement of passive solar technologies in houses with adequate solar access is easy and cost-effective.
Figure-5: Solar Access

Implications of Improper Planning for Solar Access

  1. The attempt of reducing energy consumption by communities is decreased considerably.
  2. It is difficult and expensive to install passive solar technologies in houses without proper planning for solar access.
  3. Houses without solar access can be costly for the government because of the increased staff time required to process variances and other requests.

FAQs

What is solar access of buildings?

Solar access simply means access to sunlight during the winter months without any obstructions from neighboring buildings and trees.

What is the purpose of building site planning for solar access?

The goal of site planning for solar access is to permit the south side of the building to be exposed to as much sun during the winter months as possible.

Why is solar access important?

1. Solar access is a crucial component of passive solar design
2. The property's design might get rejected by local authorities if it overshadows closed buildings without plausible reason.

What are the benefits of solar access?

1. Improve the energy efficiency of buildings at almost no additional costs.
2. If combined with other sustainable building techniques, it can reduce energy consumption considerably.
3. Placement of passive solar technologies in houses with solar access is easy and cost-effective.

What are the implications of improper planning for solar access?

1. The chance for energy consumption reduction by communities is decreased considerably.
2. It is difficult and expensive to install passive solar technologies in houses without proper planning for solar access.
3. Houses without solar access can be costly for the government because of the increased staff time required to process variances and other requests.

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