If the glazing-to-net-floor-area percentage is less than 15% then the SANS 10400XA prescriptive deemed-to-satisfy compliance route may appear to be the most simplistic path to follow on F1 classification projects. We have modelled and assessed numerous retail stores this year and without fail it has proven that substantial long-term running cost savings can be brought to bear in every instance by rather using a rational design assessment to understand and develop designs solutions for the project.
On a new 5,000m2 SPAR project we assessed recently in Durban North, KZN, the building only had 9% glazing and yet through a rational design assessment we are able to help identify ways of giving the client an estimated R42,000 per month savings on their electricity bills over what could have been achieved through a prescriptive design solution.
An analysis of the two routes to compliance is quite frightening when the energy use is compared:
Deemed to satisfy route: 368 kWh/m2.annum energy consumption & 115.9 VA/m2 energy demand
Rational Design solution: 236.3 kWh/m2.annum energy consumption & 79.1 VA/m2 energy demand
Although the relatively energy-hungry prescriptive deemed-to-satisfy route will meet the requirements of the SANS 10400XA requirements with lowest specification in terms of hot water heating, HVAC performance and relatively inefficient lighting at 24W/m2 the energy usage and demand performance can be reduced in this instance by around 35% if the performance route is rather followed.
The SPAR building was simply specified with cavity wall construction, single-glazed clear glass throughout, reduced flat slab roof insulation, energy efficient lighting, heat recovery for hot water generation and an efficient HVAC system at little to no extra capital cost on construction.
If you are working on any F1 classification project be wary of thinking that the seemingly-simplistic prescriptive route is the right way to go when it in fact may not be serving your clients best interests in the least!