Microsoft Word - Zero Energy Retrofit Case Study of a Chalet in Ain-Sukhna, EGYPT.docx - Zero Energy Retrofit Case Study of a Chalet in Ain-Sukhna, EGYPT.pdf

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• Renewable energy resources in Egypt include solar, wind and biomass. For example, the average annual total irradiation is above 2409 bankable kWh/m2 per annum with approximately 3300 hours of full sunshine and the annual monthly averages of wind speed range from 5.0 to 7.1 m/s

• However, these resources are generally not yet exploited in the Egyptian building sector on any scale.

• 3. AIN SUKHNA CHALET ENERGY ANALYSIS 3.1 Existing Situation The Chalet is located in Ain-Sukhna city (Lat., 29° 32.0' N. Long., 32° 24.0' E) on the Gulf of Suez, 140 km east of Cairo and was built in 1992. The modular chalet unit represents the typical tourist accommodation type that is spread along the Egyptian Red Sea Riviera. The chalet is the first unit of an array of single-story units with a back and front garden. The total floor area of the chalet is 64m2 plus 60m2 for the terrace and garden. The chalet consists of a main living room with a small kitchenette in addition to a bedroom and a bathroom. Openings have an east-west orientation and the living room is facing the sea on the east. The external wall construction is made out of 250mm silt- brick integrated within a reinforced concrete structure (roof

• and columns). There is no thermal insulation, all windows are single glazed (3mm glass) and transparent. Also the Chalet is exposed to high solar irradiation, which drove the owner to plant dense vegetation all around the building. The chalet has a window type air conditioner (AC) for cooling, three excessively used ceiling fans (CF) and an electric heater for domestic hot water (DHW)

• After investigating the bioclimatic site conditions, the research defined the internal loads for the Chalet. Since electricity is the only source of energy for the Chalet, a month-by–month electricity consumption compilation was done. The number of total kilowatt hours (kWh) consumed in 2006 was 3486 kWh. Next, a field survey for appliances and lighting usage patterns was conducted for the month of August. The results of this survey, in addition to the monthly bills were collected and utilized to breakdown the total consumption and calculate the cooling and heating loads

• 4. DESIGN STRATEGIES 4.1 Strategy 1: Reduce Heat Gain, Thermal Skin – Insulation: The first step that can reduce heat gain significantly is to install an external thermal insulation. This was done to maintain effectiveness of thermal mass. The strategy suggests building new external walls, 250mm wide, from

• silt-brick working as a second-skin façade over the original. Also a 60 mm polystyrene insulation is recommended to increase the wall resistance up to R-3.70 (Egyptian Standard = R-1.1). For the roof, an 80 mm polystyrene insulation will increase the resistance up to R-5.23 (Egyptian Standard = R- 2.8). Table 1 describes the material characteristic and R- Value for the new building skin construction. This new strategy complies with the Egyptian Energy Standard (ECP306-2005), which is implemented on a voluntary basis. Moreover, to achieve high albedo surfaces, the walls will be painted with white semi gloss paints and the roof tiles will be made from white cement

• Shading and Windows: Also to avoid the solar gains in the chalet and consequently reduce the cooling loads, openings require improved glass surfaces and shading devices. Overhang shading devices should admit low angle sun in the morning or winter when heat is needed, screen the sun in the middle of the day and in summer when overheating is a risk. The first step is to replace all single pane windows with 2.5R double-pane windows (low-e) with a 6mm air space. Second, is to add shading devices to the east-façade. Since the main window is facing east and the window dimensions are 2.4 m by 1.2 m the chalet requires an overhang. The overhang will be cantilevered for 1 meter, to protect the living room from the sun between April and Octobe

• Strategy 2: Reduce Internal Loads Daylight and Appliances: The existing daylighting system is acceptable in the chalet based on the owner’s opinion. The openings were mainly designed to maximize the view therefore glare cannot be avoided without compromising the view. Meanwhile, the existing window wooden blinds are a sustainable solution to manually control illuminance and daylight distribution. Besides, all artificial lighting sources are going to be replaced with low energy lamps in addition to efficient appliances. In particular, all 80 watts CFL will be replaced with efficient 50 watts CFL. Next, the 1200 watt AC will be replaced with an efficient 900 watt unit

• Strategy 3: Passive Cooling During spring and autumn, passive cooling can be provided through natural ventilation. The building should be prepared to allow air to flow through the building at night and when outside temperature is lower than inside the building. The chalet design was revised to make sure that openings and doors with built-in vents will allow cross air ventilation. In fact, while verifying the success of this strategy is not within the scope of the study, however, in a later phase of the research its effect could be quantified through real measurements and computational fluid dynamics (CFD) simulation

• Strategy 4: Solar Thermal System (STS) A market survey suggested using the thermosyphon for economical reasons. The NGO-150 solar thermosyphon was selected. The thermosyphon has an annual solar fraction of 93% (5 %) and the daily consumption is 150 liter/day with an average temperature of 50 o C. The expected energy produced by this system is equivalent to 1,224 kWh/yr. The 2m2 unit will be installed on the roof and inclined to the south with a tilt angle of 42o from the horizontal because the thermosyphon will be turned off during the summer. Besides, the existing electric water heater would be kept as an instantaneous back up water heater.

• Strategy 5: Solar Electric System The electricity consumption analysis shows that the chalet consumes approximately 3.5 MWh/yr. After implementing the previous mentioned strategies to the model, TRNSYS [11,12] simulation estimated a reduction of 1600 kWh/yr. This step was fundamental prior to sizing the PV panels. Now, the chalet needs approximately 2 MWh/yr. After consulting several companies in Egypt, most of them agreed that 10 m2 of PV panels will yield approximately 2.1 MWh annually. The chalet is considered as grid-connected with a 1.1 kWp system. In fact, the available modules in the Egyptian market are assembled from polycrystalline cells (module efficiency 10.5%) and can be mounted on the flat roof with 29 o inclination. Figure 5 shows the predicted system output

• Strategy 6: Wind Turbines System Despite several existing wind farms that are spread all over the Red Sea Coast, there is no trace for small-scale wind turbines in Egypt. Even research centers did not install any of those recently marketed small wind turbines. The study however, will proceed with building up the case, using a small-scale wind turbine (D400 Wind Turbine). The total weight is 15 kg and the diameter is 1.10 m. The turbine head will stand 2.20 m above the roof requiring an average wind speed of 5 m/s. In addition, an inverter, which turns the wind-generated electricity from DC to AC, has to be provided. The turbine will produce between 0 and 10 kW hours per day, depending on the prevailing wind speed. A realistic annual yield would equate to 1.8 kW hours per day

• In fact, passive design strategies achieved a total annual energy saving of 48%. The largest savings was achieved from the building envelope retrofit (48% savings), followed by the installation of the solar thermosyphon for space heating and domestic water heating (26% savings). Also improving the appliances efficiency helped in cutting down the total energy demand (20% savings). The implementation of the previous strategies had a significant impact in reducing the chalet energy consumption to 1872 kWh/yr. The PV panels were seized to deliver 2100 kWh/yr with the addition of a small-scale wind turbine, which is expected to deliver 660 kWh/yr. In fact, the chalet meets the zero energy objectives. Table 3 shows the expected annual yield after implementing the active strategies. The study shows that an annual energy surplus design could be achieved by combining all strategies.