Climate consultant Analysis
This analysis showed that sun shading of windows, internal heat gain, passive solar direct heat gain high mass, heating and humidification, high thermal mass, natural ventilation cooling and fan forced ventilation cooling(in this order) were the design strategies that I needed to pay attention. This, in addition, to achieving net zero energy or lowering energy consumption as much as possible are the main things that drove the decision making process for me in terms of the HVAC system choice.
Your overall HVAC system strategy
I chose to focus on a design that did not require a mechanical HVAC system, given my project location in Nanyuki, Kenya. Most of the designs that I drew my inspiration from in Kenya are designed to only make use of natural cooling and heating systems. This is usually in attempt to reduce building operation energy and hence cost as much as possible. In addition, this is a more sustainable way of designing and building, and wherever possible, I will always vouch for a fully natural or hybrid HVAC system for our buildings
Your heating strategy and how you implemented it in your design
For my heating strategy, I heavily relied on the large south facing windows that would bring in sunlight. This would then get absorbed by the thermal mass walls and concrete floors. The idea was was to have the right amount of south facing windows and couple that with the right thermal mass (thick walls and floors in my case). The thick walls (plaster finish) and concrete floors are used to keep the spaces from not getting to hot during the day and then radiating heat to warm up these spaces when it gets cold at night. The other additional part of the design to take into account for this strategy to really work would be to make sure to use the right amount of glazing for these windows, to avoid overheating on days when it’s too hot outside. There is also a a large overhang on the south side to help minimize overheating when the sun is high up during the summer.
Large south facing windows picture below: for direct solar heat gain
Thick walls for effective thermal storage
Thick floors for effective thermal storage
Your cooling strategy and how you implemented it
I drew my cooling strategy inspiration from the design of the Swahili apartments(right) located in the coastal part of Kenya and that of Start up Lyons campus (left) located in North western part of Kenya. The thick walls made from local stone with a plaster finish, the concrete floor and the green roof, are used to help absorb heat during hot days and prevent the inner part of the building from getting too hot.
Both of these buildings inspired the idea to add ventilation shafts to my building for cooling and air circulation. The shafts are meant to extract warm air upwards while fresh air is introduced into the building through low lying louvres to the east of the building and in both south and north views, at different levels of the building. The louvres are meant to bring in air and they are located above windows and above the 9’ to ensure that air circulation is not negatively affecting occupant comfort in the spaces.
Cooling/ ventilation shafts to extract warm air from the building
Louvres to allow cool air to flow into the building
Blue is warm air flowing out of the building
Red is cool air flowing into the building
Lower east louvres to let cool air into the building from the bottom
Any special HVAC system challenges that you encountered
One special challenge was modelling louvres into the curtain walls and might still need the help of the teaching team to finish this part. At the moment, the parts with curtain walls, don’t have any embedded louvres which might hinder proper air circulation