22-0120 ZE Residential Back-up Generator

QUESTION

The  project site (1233.71 sq.m) with a built-up area of 884.21 sq.m is in Panaiyur, Chennai India. It is a residential project with a G+1 structure.

1.2.2 Energy Use Clarifications: Backup systems for emergency power requires that

A.     If the programmatic needs of the project require an emergency power system, one which is not utilized for standard building operations, it may be excluded from the project scope and associated energy calculations.

B.     The use of combustion-based emergency backup power systems is discouraged but allowed to be utilized in Zero Energy projects.

The project is a residential project located in Chennai, Tamil Nadu, India. Because of the nature of the project being residential, the occupancy is expected to remain at 100% throughout the performance period.

The climate conditions of the project location should be noted since it helps to understand the energy needs.

The  project is located in Chennai, which is hot and humid year around, with some seasonal changes in perceived humidity. The site also experiences high frequency of unannounced load shedding. Thus, to meet thermal comfort conditions, such a situation necessitates the need of emergency energy backup in this project.

1.1  Diesel Generator for emergency energy backup

The project location frequently experiences unannounced load shedding. The frequency of which increases during the summer seasons, night-time blackouts are also experienced.

The climate of the context demands the use of higher power consumption cooling systems, which gets amplified during the summer season. In such a context, the capacity of the battery energy backup should be considered. The energy capacity of a battery will be insufficient to power the house throughout the night where large appliances with higher power consumption will be necessary to maintain thermal comfort.

In a site where hour long blackouts are greatly expected, battery backup inverters are not powerful enough to start and run powerful appliances.

To keep in alignment with the intent and to reduce the impact on the environment, other alternatives for emergency energy backup that ensures occupants comfort conditions were studied, and use of Natural gas/ Propane generators were considered.

Piped natural gas network is yet to be completely established in India and is not widely available. Less than 1% of cities in India has access to piped Natural Gas. Tamil Nadu, Chennai where our project is located lacks Piped Natural Gas Network and does not have piped natural gas supply. Thus, setting up a Natural Gas/ propane gas back up system is not possible for this project.

The project is a Net Zero project which is based on a PV energy system and grid tied. Diesel Generators will only be used if both Solar PV and grid fail to provide electricity to the project.

2.    PROPOSAL

We propose the use of a Diesel Generator instead of a battery-based emergency backup or Natural gas/ Propane generators because of above mentioned reasons. We propose to reduce the carbon produced due to using diesel generators. To achieve this, project includes multiple elements.

We propose the use of a Diesel Generator instead of a battery-based emergency backup or Natural gas/ Propane generators because of above mentioned reasons. We propose to reduce the carbon produced due to using diesel generators. To achieve this, project includes multiple elements.

1.1  Biophilic Landscape Design

Including nature in the built environment through biophilic landscape design

a.     Green spaces, water features, and abundant plants are provided on the site level.

b.     Pockets of green terraces are strategically distributed throughout the zoning of the house, such that each space on every level has green area included in it.

c.      A green trellis running along the deck on the first floor adds to green elements of this project.

1.1  Reduction during construction

Reduction during construction stage of the project

a.     Steps are taken to choose more sustainable building materials that help with reducing the overall carbon footprint.

b.     One such material being GGBS, Ground granulated Blast- Furnace Slag which is a by-product of steel making is substituted in the place of concrete.

ANSWER

The Institute does not see a basis for approving use of a fossil-fuel-based generator during the conditions described in the post.

The post offers no data or analysis to support the statement that higher power consumption cooling systems are required, or details as to why widely available extremely energy efficient cooling technology would not suffice. Nor has the team identified any efforts to minimize the intensity of energy consumption and thereby the need for, or size of, back-up systems, by for example, maximizing passive conditioning strategies. Further, the post does not provide data or analysis showing what back-up energy could be provided by battery and why it couldn't contribute to some or all of the need. Typically, an emergency load is considered to be only that which is required to sustain critical life systems and is therefore often smaller than that of routine daily operations.

But fundamentally, the team has not demonstrated that the conditions under which the generator is proposed for use constitute an emergency. Rather, the scenarios described appear to be routine day and evening demands of normal operation.

The intent of the Zero Energy program is that projects live within the carrying capacity of the site. This in turn drives both reduced energy consumption and increased resilience.

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