Book - School of Science and Technology

68 The building in summerfrom simple orientation-dependent glazing ratios, through limiting values of peak dailyaveraged solar cooling load, to full dynamic calculation of overheating risk. The morecomplex the method used, the more the design can take advantage of the benefits offeredby solar control glass, shading devices, thermal mass and night ventilation etc.It should be noted that the requirement to control solar overheating does not imposeany restriction on the use of air-conditioning. What it does do is to make the buildingcapable of being kept reasonably comfortable in the absence of air-conditioning (providedinternal gains are modest). The regulations do, however, impose requirements on airconditioningand mechanical ventilation systems, in that if they are installed, they shouldbe `reasonably efficient'. The implications of this are covered in Chapters 13 and 14.Primary InfluencesThe level and pattern of energy use in a building, particularly in summer, has its beginningwhen an architect accepts a brief from a client, on behalf of a full design team, and theinitial composite sketch plans are developed. They are affected throughout the laterdetailed design and construction process (and until the day of demolition) by a host ofinfluences including:. Building exposure: orientation; shape; modules; mass; thermal insulation; glazing; solarshading; plant room siting; space for service distribution.. Plant and system design to match the characteristics of the building and to meet theneeds (known and unknown) of the ultimate occupants.. Commissioning and testing of the completed plant and the adjustment to ensure that itoperates as designed in all respects.. Operational routine as adapted to match the building use in occupational pattern,working hours and the like.. Level of maintenance provided to both building and plant; energy audits; preservationof records and updating.Some of the characteristics which lead towards conservation of energy have been dealtwith previously in Chapter 2 and will be explored further in this present chapter. In termsof primary energy, Figure 3.2 illustrates how building form can influence consumption,the three blocks in the histogram, identified as A, B and C, being taken from publishedwork*and related to consumption per m 2 of floor area. If, however, consumption isrelated to occupancy and the advantage of open planning is taken into account, block Dmust be substituted for block C and it will be noted that the apparent penalty re block A(but for a greatly improved environment) is then halved. This example has been introducedhere in order to illustrate that energy use per unit area may not necessarily be theappropriate criterion in all cases.Similarly, the thermal balance point of a building was a term which acquired a specificmeaning in the recent past. It was then defined as that outside dry bulb temperature atwhich, if all heat generated within the building from lighting, occupancy and machines,etc., were to be distributed usefully, energy from a subsidiary source would be unnecessary.A low balance point, then proposed as a standard of excellence, was later demonstrated tobe quite the reverse since it implied a requirement for mechanical cooling at any higheroutside temperature. The term has since fallen into disrepute.*Dick, J., Ambient Energy in the Context of Buildings. CIBS/RICS/DOE Conference, 1977.