Case study 2

9.3.1 Description

Group 2 comprise 23 architecture students who participated in a five-day workshop to research, analyze and propose a design for a NZEB using BPS tools. The workshop started from 19-23 February 2011. The student participants included undergraduate students from the architecture department at Faculty of Fine Arts in Cairo. The undergraduate students ranged from 2^nd year to 5^th year students. The students comprised five teams, consisting of four to five students per team. Each team was responsible for an individual design concept for a net zero energy residential cluster. The majority of the work took place in the design studios of the EECA in Cairo. In conjunction with the studio environment, keynote speakers, invited guests, and other interested parties participated in the educational experience.

The workshop focused on developing a conceptual plan for eight residential units utilizing principles of energy efficiency, environmental design, community and art. BPS tools and sensitivity analysis had to be used in the decision-making process and the results may have adverse or unintended effects on the other principles. The workshop title objective was assessing the effectiveness in integration building performance simulation (BPS) tools in the design process of net zero energy buildings. During the workshop process, design duties among team members were necessary to ensure consistency. The first design created without lecturing and without simulation tools was used as control for the first and second interventions. The second design was created after receiving lectures on NZEB design and the third design for both groups was after using ZEBO and DesignBuilder simulation tools.

9.3.2 Design Project

The residential cluster had to be located in the 5^th Settlement of New Cairo, a new satellite city of Cairo. The cluster comprised 8 apartment units each 150m², hosts 5 family members and had to be mechanically air conditioned.

Students were asked to arrange the eight units into a cluster. Figure 9.2 shows different possible arrangements of the eight units. Students were not restricted to use anyone shown in the figure. Students had to define the physical performance of the design parameters.

Figure 9.2 Different possible arrangements of the eight residential units

9.3.3 Design Outcomes

9.3.3.1 Blue

The final design of the Blue group was based on clustering the residential apartment units horizontally on two floors. The idea was then to create a shed protecting the roof and south facade as shown in Figure 9.3. The building envelope is using bearing wall system for the building structure. The walls cross section should be combined from a 0.15m brick wall, 0.1m poly-urethane insulation layer and then 0.1 mud brick wall with a U-value of 0.7 W/m² K. The roof U-value is 0.4 W/m² K. The WWR is 30% and all glazing is a double glazing 6mm/6mm with air filling. The east and west facades had a projection factor of 0.6 equivalent to 1.2 m. The occupant density was 5 persons per 150m². The minimum fresh air requirements were 5 litre/second/persons and the target for lighting was 300 lux. The lighting density was 19W/m². The air conditioning system was a VRF system with a COP of 1.7. For the active systems the participants estimated 16 m² for all apartments for DHW. For photovoltaics they selected mono-crystalline cells (efficiency 14%) resulting into 28 panels mounted on the roof with a total surface area of 14 m² per apartment.

Figure 9.3 Workshop 2 the design of the Blue Group

9.3.3.2 Green

The final design of the Green group was based clustering the residential apartment units on a curved arch as shown in Figure 9.4. The building envelope is using bearing wall system for the building structure. The walls cross section should be combined from a 0.15m brick wall, 0.5m air gap and then 0.15 brick wall with a total U-value of 0.9 W/m²K. The roof U-value is 0.33 W/m² K. The WWR is 35% for the North facade and 20% for South, East and West facades. The glazing is a double glazing 6mm/6mm with air filling. The east and west facades had a projection factor of 1.8. The occupant density was 5 persons per 150m². The minimum fresh air requirements were 5 litre/second/persons and the target for lighting was 300 lux. The lighting density was 19W/m². The air conditioning system was a VRF system with a COP of 1.7. For the active systems the participants estimated 6 evacuated tube water heaters each is 8 by 2.5 m.

Figure 9.4 Workshop 2 the design of the Green Group

For photovoltaics they selected mono-crystalline cells (efficiency 14%) resulting into 28 panels mounted on the roof with a total surface area of 16 m2 per apartment.

9.3.3.3 Orange

The final design of the Orange Group was based on clustering the residential apartment units around a courtyard. The courtyard is open from the North side and creates a U-shape cluster as shown in Figure 9.5. An extra shading screen is protecting the south wall and overlaps the roof. The building envelope has a wall cross section combining 0.15m brick wall, 0.5m polyurethane insulation layer and then 0.15 brick wall with a U-value of 1.42 W/m² K. The roof U-value is 0.43 W/m² K. The WWR is 30% and all glazing is a double glazing 6mm/6mm with air filling. The east and west facades had a projection factor of 0.6. The occupant density was 5 persons per 150m². The minimum fresh air requirements were 5 litre/second/persons and the target for lighting was 300 lux. The lighting density was 19W/m². The air conditioning system was a VRF system with a COP of 1.8. For the active systems the participants estimated 16 m² for all apartments for DHW. For photovoltaics they selected mono-crystalline cells (efficiency 14%) with a surface area of 16 m² per apartment.

Figure 9.5 Workshop 2 the design of the Orange Group

9.3.3.4 Purple

The final design of the Purple Group was based on clustering the residential apartment units around a courtyard. The courtyard is open from the North side and creates a U-shape cluster as shown in Figure 9.6. An extra shading screen is protecting the south wall and overlaps the roof. The building envelope has a wall cross section combining 0.1m brick wall, 0.1m poly-urethane insulation layer and then 0.1 concrete block wall with a U-value of 1.43 W/m² K. The roof U-value is 0.76 W/m² K. The WWR is 50% for the North facade, 40% for the east facade, 25% for the West facade and 35 for the South facade. The east and west facades had a projection factor of 0.75.

The occupant density was 5 persons per 150m². The minimum fresh air requirements were 5 litre/second/persons and the target for lighting was 300 lux. The lighting density was 19W/m². The air considering system was a VRF

system with a COP of 1.8. For the active systems the participants estimated 16 m² for all apartments for DHW. For photovoltaics they selected mono-crystalline cells (efficiency 14%) with a surface area of 18 m² per apartment.

Figure 9.6 Workshop 2 the design of the Purple Group

9.3.3.5 Red

The final design of the Red Group was based on clustering the residential apartment units around a courtyard as shown in Figure 9.7. An extra shading screen is protecting the south wall and overlaps the roof. The building envelope has a wall cross section combining 0.1m sand stone, 0.02m gypsum and a 0.25 AAC block wall with a U-value of 1.3 W/m² K. The roof U-value is 0.36 W/m² K. The WWR is 17% for the North facade, 17% for the east facade, 9% for the South facade and no openings for west facade. The east facades had a projection factor of 0.6 and the east facade had a 0.9 projection factor. The occupant density was 5 persons per 150m². The minimum fresh air requirements were 5 litre/second/persons and the target for lighting was 300 lux. The lighting density was 19W/m². The air conditioning system was a VRF system with a COP of 1.8. For the active systems the participants estimated 16 m² for all apartments for DHW. For photovoltaics they selected mono-crystalline cells (efficiency 14%) with a surface area of 18 m² per apartment.