5. INDOOR STUDIES | COMPUTER LAB 02

5.7 TECHNICAL STUDIES

Changing Glazing Properties

Use of Double Low-e argon glass, which helps in reducing external heat gains during summer and internal heat loss during winters (Figure 5.7.1). This also helps in increasing daylight in the space. The thin, transparent hard pyrolytic Low-E coating allows 67% of the solar heat gain to be transmitted and 78% visible transmittance into the space, aiming at comparatively higher daylight to enter the computer lab.

Louvered Stack Ventilation

As the existing skylight is sealed due to overheating and glare during the peak times, a potential solution was considered of having a louvered stacked roof with double Low-E argon glazing (Figure 5.7.2). This would help in increasing heat loss and ventilation during summer when the temperature would rise much above the comfort band. This potential solution also helps in improving daylight during winters.

Controlled Natural Cross Ventilation

Use of natural ventilation and ventilative cooling is the potential for low operational energy use and associated low CO2 emissions and operational costs. (Dejan Mumovic et al, 2013). In addition to this, the use of night shutters was introduced during winters, which would help retain the heat generated through the systems and balance the heat losses to gains during operational hours (Figure 5.7.3).

Solar control strategies are adaptive for effective light distribution and glare prevention. Adaptability becomes a key issue when real-time control is needed to modulate between maximal and minimal exposure to the outside. The addition of louvers in the fenestration, allowing the room to run on a free-running mode, also allows reflection of incident daylight as the material of the louvers are acrylic and can be manually operated to optimize maximum daylight.

5. INDOOR | COMPUTER LAB 02

5.8 THERMAL STUDIES

5.8.1 Annual Performance

The base case scenario in this section shows annual indoor temperatures along with annual heating loads. The simulations, in this case, consider the internal floors as adiabatic surfaces, hence an assumption is made that there are no heat gains and loosed from adjacent surfaces. This can be seen as a limitation, as the results can be affected by heat exchange through adjacent surfaces. Table 5.8.1.3 shows the considered parameters used to run simulations.

The seasonal schedule pattern used in the simulations is 10th January to 25th March and 25th April to 18th of December as an operational period with the rest being considered as a vacation.

A temperature of 20°C is considered as per the simulations for the heating schedule. Hence a minimum of 1 and a maximum of 13 occupants have been considered throughout the cases, with a floor area of 25.20m2

Appliance load of 100 W per system as 60% working efficiency is considered, along with varying occupancy patterns. Lighting loads were assumed to be 5 W/ m2, considering the base case scenario.

Figure 5.8.1.4 shows the annual graph for the base case and a free-running case with maximum and minimum occupancy. It was observed that the heat generated by the systems was one of the major reasons for heat gains, hence most of the period from the free-running case is ranging away from the comfort zone. As a result, it is observed that heating is required.

Figure 5.8.1.1 shows the annual heating demand with an energy consumption of 32 W/m2. Annual heat gains and losses, from different parameters for the base case, can be seen in figure 5.8.1.2

Weather File London St James Park

Infiltration 1.0 ACH

Required Fesh Air 8.5 l/s

People Activity 115 W

Lighting 5 W/m2

Appliances 100 W per System

5. INDOOR | COMPUTER LAB 02

5.8 THERMAL STUDIES

5.8.2 Typical Summer Week

The thermal performance for the base case, over a typical summer week, is seen in this section. As seen in figure 5.8.2.1, the period chosen for this week dates from 6 July to 12 July, where the outdoor temperature is ranging between 12°C to 21°C. The daily global horizontal solar radiation is seen to reach a maximum of 850 Watts. The indoor thermal comfort band is between 22°C to 27°C for the entire month. It is important to note that the operational hours are considered from Monday to Saturday, with Sunday being non-operational.

According to the simulation results it can be seen that, for free-running mode, with maximum occupancy, the temperature ranges from 19.5°C (minimum) to 27°C (maximum). However, with minimum occupancy, there is no significant change in temperature as the heat gains are more than heat losses through ventilation. With regards to the base case, it is seen that operational hours is within the comfort zone. The indoor temperature can be achieved within the comfort band, with the addition of adequate natural ventilation during operational hours.

Annual heat gains and losses, from different parameters for this case, can be seen in figure 5.8.2.2. It is observed that the air exchanges per hour, ranging from 4.5 ac/h to 18.5 ac/h help in improving the thermal performance of the space (Figure 5.8.2.3).