BUILDING GREEN: From Principle To Practice
The EMC office building cum Energy Management Institute complex consists of a 43,000 sq. ft headquarters office building in a 2 acre landscape and further 2 acre land demarcated for organic cultivation and social forestry, including parking and driveways, while retaining three old buildings of about 5,000 sq. ft in the premise as guest houses for the Energy Management Institute. The building is exemplary in its resource efficiency. Designed and built within a modest budget, the actual metered energy usage averages 12.5 kWh/sq. m-year in summer and about 10 kWh/sq. m-year in winter/rainy seasons, which along with renewable energy generations from the solar PV installations onsite assured that the payment to utility company towards energy cost is zero.
The Energy Management Centre (EMC) Kerala, with support from the Government of Kerala, made a commitment to sustainable and energyefficient building practices when it initiated the design of its office and training institute near Sreekariyam, Thiruvananthapuram, in Kerala. After considerable challenges in balancing design requirements, energy efficiency, sustainability, and construction cost issues, its dedication resulted in a highperformance, low-energy, and sustainable facility on a speculative office building budget. The building was inaugurated in February 2016.
Passive and active energy optimization was used to assist in the design of this naturally ventilated and passively cooled architecture. In this building, cooling solutions included natural ventilation with night cooling, using principles of stack effect combined with innovative material use. The design attempted a seamless integration of light, form, and the surrounding greenery.
The project design pre-dates the LEED IGBC (Leadership in Energy and Environmental Design–Indian Green Building Council) N.C v1.0 rating system for new construction and other similar best practice design guidelines available today. The important details of the building are as follows:
- Built-up area: 43,060 sq. ft
- Conditioned area: 9,794 sq. ft
- Number of floors: Ground + 1 floor
- North orientation: 205°
- Operating hours: 10:00 a.m. to 5:00 p.m. for 6 days in a week
- Climate zone as per ASHRAE 90.1: 1A/warm and humid as per ECBC 2007
The design process was driven by commitment to a goal of low energy use and the application of computer simulation tools to evaluate building options supporting that goal. The design goals were as follows:
- Reduce building energy consumption: The EMC facility should serve as an example of innovative energy-efficient techniques adapted to commercial buildings.
- Other sustainable design goals: Selecting appropriate building materials; reducing the amount of building materials; and improving the ecology of the site. • To maximize solar access for daylighting and other solar systems and minimize east and west glass. Consider microclimatic, micro-ecological, and geological conditions. • To consider the renewable energy resources at the site and the potential for implementing solar energy systems.
The final project design integrated a number of energy-efficient strategies that are innovative, straightforward, functional, and cost effective.
Daylighting and natural ventilation: The building adopted optimum orientation of blocks to ensure that only the north and south facades are fenestration for lighting and ventilation, while the east and west facades were made minimum and closed so that energy performance is greatly enhanced, comfort conditions are improved, and initial costs associated with cooling are reduced.
Reductions in cooling loads due to daylighting strategies enabled designers to downsize air conditioning systems, which reduced the initial cost of equipment. High-performance windows also helped to minimize heat gain in warmer months and heat loss in colder months. Although windows can create glare and skylights may cause overheating, properly designed daylighting strategies can reduce both lighting and cooling energy and control glare.
The orientation of the building, the shape of the roof, and the materials used for the external envelope were designed to cut the glare and reduce the unwanted solar gain. The surrounding environment of dense deciduous vegetation and the prevailing wind directions were considered in making this structure climate responsive and more energy efficient.
The building’s section energy concept equally divides the area into different logical thermal zones. Daylight control zones follow the same configuration with the exception that private offices in the north perimeter zone are controlled by two light sensors. Occupancy sensors were planned in public spaces such as toilets to turn lights off when the sensor detects the location is vacant.
Electrical demand of lighting systems: The equivalent lighting power density levels stipulated by ASHRAE 90.1 being at 10.7 W/sq. m, the actual connected lighting power density for the building is 2.28 W/ sq. m.
The designers were keen to incorporate onsite renewable energy facilities to meet the energy needs of the building. When evaluating site design issues, it is essential to investigate renewable systems early in the process.
- Considering building-integrated photovoltaic systems for electricity production, the rooftop of the building provides ample space for solar PV generation. Installing building-integrated solar thermal systems for domestic hot water, space heating, and absorption cooling for a future possibility was considered.
Initially, net-metered solar PV plants of 30 kWp were considered in the design stage. Later seeing the opportunity to make the building net energy positive, another 31.7 kWp through three different systems catering to different needs—10 kWp for lighting and server room air conditioning, 20 kWp for UPS charging, and 1.7 kWp for experimental set-up to run a split-type DC air conditioner—was installed. The solar panels are proposed to generate 103,000 kWh of energy.
Renewable energy usage: The total energy exported by the 30 kWp grid-connected solar PV unit is 48,160 units, which is more than the power imported to the campus from the grid. Since the building’s computer system consumed the highest amount of energy, the EMC installed a 21 kWp solar PV plant exclusively for catering the UPS load, which abates 35% of utility power. In addition, the lighting load is now being diverted into a 10 kWp PV unit with battery back-up that takes care of the lighting energy usage, which equals to another 35% of the utility power.
To assess whether the project is performing in line with the design considerations, the building was monitored for more than 1 year with regard to detailed energy use, water usage, and renewable energy generation.
The utility company (KSEBL) meter measures the total site’s electrical power for the building. An additional meter is provided after the utility meter for measuring the net solar energy being fed into the grid. Five sub-meters segregate the electrical power for the office building’s lighting panels, HVAC panels, general plug loads, and the power utility services and UPS power panel to the maintenance facilities. The total of the five sub-meters reconciles with the utility premises meter. The metered data for 2016/17 indicate the office building used 40,188 kWh for the year, which translates to 3,162 BTU/sq. ft.
Analysing the energy usage over the last year at an EPI of 9.97 kWh/sq. m-year, EMC’s new green building outperforms the EPI of BEE five-star-rated building in warm and humid region for buildings with less than 50% conditioned space. Even with a comparable star-rated building, the EMC green building saves close to 1.5 lakh units of electricity annually.
This facility creates a meaningful place that provides more than basic administrative offices, conference and training rooms, and paved parking lots, which are status quo with strip mall office developments. It demonstrates that a high-performance, energy-efficient, environmentally responsible small office building is possible on a speculative office building budget. The integrated design process coupled with an extended project team allowed the team to capture energy performance that is not possible with conventional project design approaches. The project’s energy efficiency design goals were met or exceeded. The measured results of energy performance confirm that the energy goals were achieved and are sustainable over time.
Mr K M Dharesan Unnithan, Director, Energy Management Centre, Kerala.