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MASTER PLANNING


‘The selection of KPIs is importance to assess the perceived benefits of different appraisal options.’


of the building. The areas to the west of the building are likely to feel exposed to wind acceleration while the areas to the east and the courtyards were found to be sheltered from accelerated winds. Wind studies can also help to assess the location of entrances, avoiding post occupational problems related to entrances that are too windy or large air infiltration to wards and secondary areas. To give a more complete picture of comfort


levels, and going beyond the standard scope for this type of work, a dynamic thermal and a CFD model were created of the Pinderfields Hospital. The combination of these studies allows for an estimation of the conditions within the different external areas and consequently output results for several variables including dry bulb temperature, humidity, solar gain, etc. In order to calibrate the outdoor


environments the Universal Thermal Climate Index was used. This comfort index has been recently developed and is an internationally accepted procedure for the assessment of human thermal comfort in any climate. The universal thermal climate index combines all


factors associated with human comfort, such as radiation, air speeds, temperature, into one single equivalent comfort temperature (ET) through a set calculation procedure. The UTCI has been developed for external


environments, but the scale it could be argued can apply to outdoor and semi- outdoor/internal zones within a building. This equivalent comfort temperature is


then associated to an assessment scale which is derived from the simulated physiological responses and comprises of ten thermal stress categories ranging from ‘extreme cold stress’ to ‘extreme heat stress’. The results are summarised in Figures 3


and 4 for a sheltered area (courtyard) and an exposed one; in the perimeter of the building. The simulations are shown below for the equivalent temperature. The results show that the sheltered areas


(Fig. 3) are likely to be less exposed to wind and show higher equivalent temperature values during the winter and spring seasons when compared with the exposed location (Fig. 4).


Conclusion The selection of KPIs is important to assess


the perceived benefits of different appraisal options. The design team needs to carefully choose the KPI that best represent the performance of an external area, and illustrate the intrinsic benefit to internal comfort and energy strategies. The performance of semi-external areas is determined by KPIs. As there are no


benchmarks to compare against, the design team is required to choose the KPIs that best assess the performance of a semi-external or external space. The careful consideration and selection of the KPIs is likely to be critical to achieve a more accurate picture of the performance of a semi-external area. KPIs for semi-external and external spaces are often


chosen from the following: • The number of hours excedence (above comfort criteria) for temperature, wind,


• equivalent temperature, UTCI, etc. The number of hours of full shade


• or solar exposure. • Degree of ventilation. • Energy savings. Seasonal performance.


The most recent development involving the city scale is on the use of an urban thermal model in combination with an internal dynamic thermal model. This combines the assessment of external and internal spaces to accurately predict energy consumption and assess comfort, including all individual buildings within a masterplan (large or small). New tools such as this are continually under development and are starting to be used by practitioners.


Benefits for hospital masterplanning This analytical approach offers the following


benefits: • It allows production of appropriate


building layouts, shading and shelter schemes to increase comfort.


Extreme heat stress


Very strong heat stress Strong heat stress Moderate heat stress


No thermal stress


Slight cold stress Moderate cold stress


Strong cold stress Very strong cold stress


60 58 56 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0


-2 -4 -6 -8


-10 -12 -14 -16 -18 -20 -22 -24 -26 -28 -30 -32 -34 -36 -38 -40


heat stress


Very strong heat stress


Strong heat stress


Moderate heat stress


No thermal stress Slight


cold stress


Moderate cold stress


0 10 20 30 40 50 60 %


Extreme heat stress


Very strong heat stress Strong heat stress Moderate heat stress No thermal stress Slight cold stress


Moderate cold stress Strong cold stress


Very strong cold stress Figure 4: External area Equivalent Temperatures. IFHE DIGEST 2015 93


0.00 0.00 0.00 0.15


33.06 42.04 22.14 1.24 0.00


Extreme


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