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Creative and Green
Design |
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The Rock Brook Consulting Group
offers sustainable project designs that are both creative and
linked to a “Green Approach.” This Green Approach
has successfully been implemented into numerous LEED®-certified
projects. Developed by the U.S. Green Building
Council (USGBC), the LEED green building
certification program is the nationally accepted
benchmark for the design, construction, and
operation of green buildings. Our firm is
proud to be on the forefront of implementing
environmentally innovative design aspects to promote
not only resource preservation but also occupant
comfort and well-being.
The concept we will follow has
the underlying definitions of ASHRAE for the
mechanical and electrical components.
A green building is one that
achieves high performance, over the full lifecycle
in the following areas:
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Minimal consumption due to reductions of need and more efficient
utilization of non renewable natural resources, depletable energy resources, land, water, and
other materials as well.
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Minimal atmospheric
emissions having negative environmental impacts,
especially those related to greenhouse gases,
global warming, particulates, or acid rain.
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Minimal discharge of harmful
liquid effluents and solid wastes, including
those resulting from the ultimate demolition of
the building itself at the end of its useful
life.
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Minimal negative impacts on
site ecosystems.
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Maximum quality of indoor
environment, including air quality, thermal
regime, illumination, acoustics/noise, and
visual aspects.
After carefully reviewing the
documentation, the following are scenarios we would
evaluate for the MEP design of the facility that
could be both cost effective, and “green” friendly.
There may be one or several of the below options
applied to the project.
Night Pre-cooling
Night pre-cooling involves the
circulation of cool air within a building during the
nighttime hours with the intent of cooling the
structure. The cooled structure is then able to
serve as a heat sink during the daytime hours,
reducing the mechanical cooling required. The
naturally occurring thermal storage capacity of the
building is thereby utilized to smooth the load
curve and for potential energy savings.
Air-to-Air Heat Recovery
A heat exchange enthalpy wheel,
also known as a rotary energy wheel, has a revolving
cylinder filled with an air-permeable medium with a
large internal surface area. Adjacent airstreams
pass through opposite sides of the exchanger in a
counterflow pattern. Heat transfer media may be
selected to recover heat only or sensible plus
latent heat. Because rotary exchangers have a
counterflow configuration and normally use
small-diameter flow passages, they are quite compact
and can achieve high transfer effectiveness.
Displacement Ventilation
In displacement ventilation,
conditioned air with a temperature slightly lower
than the desired room temperature is supplied
horizontally at low velocities at or near the floor.
Returns are located at or near the ceiling. The
supply air is spread over the floor and then rises
by convection as it picks up the load in the room.
Displacement ventilation does not depend on mixing.
Instead, you are literally displacing the stale
polluted air and forcing it up and out the return or
exhaust grille.
Combination Space/Water Heaters
Combination space and water
heating systems consist of a storage water heater, a
heat delivery system (for example, a fan coil or
hydronic baseboards), and associated pumps and
controls. Typically gas-fired, they provide both
space and domestic water heating. The water heater
is installed and operated as a conventional water
heater. When there is a demand for domestic hot
water, cold city water enters the bottom of the
tank, and hot water from the top of the tank is
delivered to the load. When there is a demand for
space heating, a pump circulates water from the top
of the tank through fan coils or hydronic
baseboards.
Ground-Source Heat Pumps
A ground-source heat pump
extracts solar heat stored in the upper layers of
the earth; the heat is then delivered to a building.
Conversely, in the summer season, the heat pump
rejects heat removed from the building into the
ground rather than into the atmosphere or a body of
water.
Ground-source heat pumps (GSHP)
can reduce the energy required for space heating,
cooling, and service water heating in
commercial/institutional buildings by as much as
50%. Ground-source heat pumps replace the need for a
boiler in winter by utilizing heat stored in the
ground; this heat is upgraded by a vapor-compressor
refrigeration cycle. In summer, heat from a building
is rejected to the ground. This eliminates the need
for a cooling tower or heat rejecter and also lowers
operating costs because the ground is cooler than
the outdoor air.
Water-Loop Heat Pump Systems
A water-loop heat pump system
consists of multiple water-source heat pumps service
local areas within a building and tied in to a
neutral-temperature (usually 50-90°F) water loop
that serves as both heat source and heat sink. The
loop is connected to a central heat source (e.g.,
small boiler) and a central heat dissipation device
(e.g., closed-circuit evaporative condenser or
open-circuit cooling tower isolated from building
loop via heat exchanger). These operate to keep the
temperature of the loop water within range.
The water-source heat pump
itself is an electric driven, self-contained,
water-cooled heating and cooling unit with a
reversible refrigerant cycle (i.e., a water-cooled
air-conditioning unit that can run in reverse).
Thermal Energy Storage for Cooling
Active thermal storage systems
utilize a building’s cooling equipment to remove
heat, usually at night, from an energy storage
medium for later use as a source of cooling. The
most common energy storage media are ice and chilled
water. These systems decouple the production of
cooling from the demand from cooling, i.e., plant
output does not have to match the instantaneous
building cooling load. This decoupling increases
flexibility in design and operations, thereby
providing an opportunity for a more efficient
air-conditioning system than with a non-storage
alternative. Before applying active thermal storage,
however, the design cooling load should be
minimized.
Indirect Evaporative Cooling
Indirect evaporative cooling
uses an additional water-side coil to lower supply
air temperature. The added coil is placed ahead of
the conventional cooling coil in the supply
airstream and is piped to a cooling tower where the
evaporative process occurs. Because evaporation
occurs elsewhere, this method of “pre-cooling” does
not add moisture to the supply air, but it is
somewhat less effective than direct evaporative
cooling. A conventional cooling coil provides any
additional cooling required. |
