microclimate and site planning

What is the definition and difference of macro climate and microclimate

General regional weather conditions where the measurements are often taken at airports, rooftops, and countryside stations however it may not represent the actual conditions at a building site.

Local environmental conditions surrounding a specific site and can differ significantly from macro climate.

Explain the four main effects that influence microclimate

Urban heat Islands (UHI) are urban areas that become warmer than surrounding rural areas through to heat absorption and storage (cities typically of 3 to 10° warmer than surrounding rural areas). This can be caused by dark surfaces which absorb solar radiation, reduce vegetation, dense building layouts and human activities. You can reduce this through landscaping, shading, water features, reflective materials and light surface finishes.

Topography can influence temperature, rainfall and wind exposure. At a windward slope, there is an increase in rainfall and greater exposure to wind. At leeward slope, it is more sheltered from wind therefore better building protection. at the valley, there are lower temperatures as called air accumulate and air pollution may become trapped.

Ground surface effect is one different materials store heat differently such as light sanding materials or heat and cool quick therefore it is considered a low thermal mass compare compared to heavy clay oils which heating goes slowly which is considered a high thermal mass. This is applied to external landscaping designs and outdoor comfort improvements.

Vegetation influences, solar, shedding and windspeed reduction. Strategically placed vegetation can provide shading during the summer and in the winter allow solar penetration fate leaves fall. This reduces overheating and improves comfort.

What is temperature in version?

Cold air trapped warm air, common after clear nights in valleys which causes colder temperatures and poor pollution disposal

What is the purpose of wind barriers, what is the best design and give example examples?

Why are solid barriers not effective?

When barriers reduce building heat losses and improve outdoor comfort. It is best for the barrier to be approximately 50% porous for example trees, hedges, fences and screens.

Solid barriers aren’t effective as it can create strong turbulences and reduces solar access

List some site planning rules for solar access for a northern hemisphere

Take advantage of south-facing slopes, at least one fade within +-30° of south, space buildings adequately to avoid overshadowing, place tall buildings to the north and lower building seller south, build at mid slope rather than hilltop or Valley bottom and build on a leeward slope for wind protection

Why is it generally recommended to build midway up a slope rather than at the top or bottom?

Mid slope provides a balance of better solar access, reduce wind exposure, especially on a leeward slope, avoid cold air pooling and provides more stable and comfortable micro climate

What are some general site design principles when it comes to building placement?

Similar to site planning rules, self facing or orientation, avoid overshadowing, provide wind shelter, use vegetation strategically, maintain adequate spacing and consider local terrain

Why are south facing slopes preferred in the northern hemisphere?

It receives greater solar radiation throughout the day, receives more winter solar gains, provide shorter shadows, tends to be warmer and dryer, improves passive heating potential, increases daylight availability and can reduce heating energy demand