The essay next posits three methods to be applied to reduce the peak internal temperature to optimum levels and also puts forward the methodology to be applied. It is also to be noted that te peak temperature is found after computing the mean temperature from records available and calculating the swing in temperature. The maximum swing is computed and added to the mean temperature to arrive at the peak temperature. The three methods actually applied are all hybrid ones in which both passive and mechanised cooling methods are applied. All three methods are found successful in reducing the temperature to optimum levels. This is also done with the application of technology that uses the least possible energy to achieve the maximum results. One of the objectives of the study is to apply cooling techniques that need the least possible energy and this also is found successful with the three methods. Reducing energy usage saves both costs and environmental degradation, as the essay notes.

The main purpose of the essay is to analyse three methods by which the internal temperature can be reduced to optimum levels in a particular building with particular occupancy at set times of the 24 hr period day. The specifications of the building are now being taken into consideration together with the existing heat transfer data and the calculated peak environmental temperature that is based on the existing heat transfer data.

Building Specifications

It is an office in a building in Plymouth facing west. The office is 15m * 5m * 3m with window area totalling 25. The other rooms around this office all have similar specifications. The office is utilised for 8 hrs each 24 hr day. There are 6 occupants emitting 90 W each and 5 electrical items each of 150 W. The doors and windows are closed beyond office time and the ventilation rate is 1.5 air changes per hour.

It is also given that the peak solar irradiance on a west-facing window is 625 W/at 1600 hrs on 21st June in Southeast England and the daily mean is 185 W/. The mean solar gain coefficient for the glazing without blinds is 0.25 and the alternating factor is 0.2.

The existing thermal data is tabulated below.

Table 1.: Heat Transfer Data

Surface

A(m)

U(W/m)K

AU

Y(W/mK)

AY

Lag(h)

Glass

25

3.3

82.5

3.3

82.5

1

0

Ext.Wall

20

0.57

11.4

3.6

72

0.31

9

Int.Wall

45

1

45

3.6

162

0.62

1

Floor

75

2

150

4.3

322.5

0.59

2

Ceiling

75

2

150

6

450

0.46

3

(AU)=438.9

(AY)=1089

Table 2. Calculated Sol-Air Data

Surface

Lag(h)

24h teo

24h tao

Time(h)

teo

Swing

Ext.Wall

9

24.5

16.5

0700

15.5

-9

tao

tao

Window

0

–

16.5

1600

22

5.5

All figures in blue are calculated. Please refer to Appendix calculations.

The solar radiance figures and solar gain coefficients come from CIBSE, 1986a, Table A8.1.

On the basis of the above information derived from given statistics the peak environmenta