Enhancement of HVAC Load, Energy Consumption and Energy Cost for a Proposed Residential Building, Bhaisepati, Lalitpur, Nepal
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Pulchowk Campus
Abstract
HVAC has become the most important infrastructure for ensuring human comfort in
workplace, residencies and commercial hubs. However large energy consumption by
HVAC system is the major factor limiting its usage. Proper material selection in
building construction not only ensures physical comfort but also ensures low
operational cost of HVAC system throughout the year. But deciding the proper material
of construction for low HVAC operational cost needs knowledge about the HVAC load
resulted by each of the materials available. The same gap has been intended to be filled
by comparing the energy consumption resulted due to usage of different types of
materials and equipment in constructing building.
A case study of a proposed residential building has been performed. The building model
has been generated in Autodesk Revit and HVAC load has been determined by using
Radiant Transfer Function Method, a HVAC load calculation method defined by
ASHRAE. Similarly, the gbxml file of this model was extracted and it was run for
energy simulation using Green Building Studio. The equipment like laptop, freezer,
television and microwave have been considered for calculation process. Heat produced
by light and energy consumed by them have also been considered for the calculation
and simulation process. The HVAC heating load was found to be 5.96 TOR, HVAC
cooling load was 5.36 TOR, EUI was 40 kWh/sq ft.yr. The annual energy consumption
was 55244 units of electricity and annual energy cost was NRs. 710191. The simulation
was run for operating the AC for 24/7 schedule.
The above processes were repeated by varying alternative options for walls, roofs,
windows, equipment and sensors. Total of 1240 energy simulations were run and
Energy Use Intensity (EUI) were compared for different materials. Walls described by
ASHRAE edition 19 and 18 along with common walls used in Nepal were used for
running simulations. Similarly, roofs were varied. Variation in windows, equipment
and sensors option was made based upon the previous literatures.
After running all simulations and comparing the results, it was found out that wooden
wall resulted in least EUI of 198kBTU/sqft.yr. However due to construction trend, it
was not used and prefab that resulted in least EUI of 231 kBTU/sq.ft.yr among
commonly used construction material in Nepal, was selected. In case of roof, R60 roof
resulted in least EUI, but casted concrete roof was selected based upon the availability.
Window with 0.3 wall window ratio, 2/3 window height shading and triple pane low-E
v
glass resulted in least EUI. It was possible to make in aluminum frame. So, it was
finalized. Among different types of HVAC equipment for residential purpose, package
terminal heat pump resulted in least energy consumption with EUI 122 kBTU/sq. ft.yr.
Use of occupancy sensor and lighting sensor was also done. After finalizing all these
parameters, model was regenerated using all these parameters and HVAC load, energy
consumption and energy cost were calculated.
The final building was found to have HVAC peak heating load of 2.88 TOR, peak
cooling load of 3.8 TOR, energy consumption of 37420kWh and energy cost of NRs.
478486. The EUI was decreased from 40 to 29 by this work. By simple alteration of
building parameters without modifying any layout, rooms and outlook, HVAC load was
seen to have decreased by large portion. Energy saving by almost 32% and energy cost
saving by 33% was possible by this simple work. However, the cost involved in
construction of enhanced building is higher than proposed building. But the cost is
balanced by energy cost in 38 months.
Description
HVAC has become the most important infrastructure for ensuring human comfort in
workplace, residencies and commercial hubs.
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Citation
MASTER IN SCIENCE IN MECHANICAL SYSTEM’S DESIGN AND ENGINEERING