10 July 2020

Table of Contents for Greenitiatives


The load factor


An integrated design approach is necessary, including the right choice of HVAC systems, to increase the overall energy efficiency of the building, reports ANUJA ABRAHAM.   


The increase in awareness about sustainability and its high return on investments has brought more clientele to green consultants.  But still there is not enough emphasis on creating sustainable, self-sufficient structures which is incidentally possible only through an integrated approach. HVAC systems are more often than not an afterthought in the design process.  Since the HVAC equipment are expensive and have a long life, it is difficult to replace an underperforming system without adding a significant amount to the overall cost. The performance of the HVAC systems will often depend on the solar orientation of the site, design of the building, choice of roofing, facade etc. Solar gain through windows, air filtration, heat load from artificial lighting will all have considerable effect on the HVAC. 

If one has planned spaces to bring in adequate natural light into working spaces, then the solar orientation in site planning and building aspect ratio (length to width dimensions) are critical to reduce the HVAC load. External shading devices, reflective light shelves will prevent glare and heat gain while bringing natural light to occupied spaces.  An integrated design approach is composed of multiple factors, from considering the materials that go into creating building envelope to fenestration, insulation, lighting systems, occupancy and more.

The efficiency of chillers and heaters affect the performance of the HVAC systems. If the load on a system can be trimmed, it may be possible to reduce the size of the HVAC unit as well. Optimising the performance of the air distribution system may provide an opportunity for further reductions in chiller or boiler size. A more difficult issue with the conventional design process is the lack of incentive to innovate and "right-size." Oversizing of HVAC is often a serious problem where load intake is often miscalculated with inaccurate information about temperatures.

While deciding on the thermal barrier for a building it is ideal to know that doubling the thickness of insulation may increase the cost but, on the other hand, it will double the insulation's R-value and cut the heat loss in half. By doubling insulation from R-10 to R-20, there will be about 2.4 per cent reduction in the size of the cooling plant, 6 per cent less cooling air volume, and a 10.3 per cent reduction in the size of the heating plant. Added insulation reduces overall building cost primarily because it reduces the amount of space required to house mechanical systems. Stopping air leaks is just as important as — maybe more important than — adding insulation. Unless builders prevent air from leaking through walls and ceilings, insulation alone won't do much good. There are energy modelling software and consultants with the know-how on the building performance testing industry who can ensure the optimum performance of the systems. The investments made on a good software can be justified by the savings available from load reduction and HVAC savings. Not to forget an ambient temperature is crucial for one’s well-being and overall optimum performance of employees.

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