METHOD OF SUPPLYING HEAT PUMP ENERGY IN BUILDING RETROFITS

METHODE D'APPROVISIONNEMENT EN ENERGIE DES THERMOPOMPES DANS LES REAMENAGEMENTS DES IMMEUBLES

English Abstract

Heat pumps, either air-source or ground source, provide a highly efficient
means of
delivering space heating and cooling. Typical solutions for retrofiting heat
pumps to
existing buildings' heating system are often costly and/or limits the
effectiveness of the
heat pump's ability to deliver heat to the building. The nature of the
invention consists
of delivering heat pump derived energy to the building through its ventilation
system.
Specially, heating/cooling coils supplied by the heat pump are installed
either in,
upstream or downstream of the building's air handling unit(s) (AHUs). The heat
pump
supplied coils thereby can provide base-level heating to the building via the
ventilation
air, essentially utilizing the ventilation system as a forced-air heating
system. The
process of adding heat coils and associated piping loop to the building's
ventilation is a
relatively minor retrofit, causing limited building disturbance and is an
inexpensive
retrofit.

Claims

3A
THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of delivering space-heating energy.
2. The method of space-heat delivery claimed in Claim 1 wherein said heat is
generated from a heat-pump, either one or several air-to-air and/or ground
source heat pumps.
3. The method of space-heat delivery claimed in Claim 1 wherein the heating
energy is supplied to existing buildings.
4. The method of space-heat delivery claimed in Claim 1 wherein the
application is
a retrofit to an existing building.
5. The method of space-heat delivery claimed in Claim 1 and Claim 3 wherein
said
heat is distributed by raising said building's ventilation air temperature.
6. The method claimed in Claim 5 consists essentially of utilizing said
existing
ventilation system as a forced air heating system.
7. The method claimed in Claim 5 consists of one or several heating coils
installed
in said ventilation system to transfer the heat from the heat pump(s) to the
ventilation air.

4
8. The method claimed in Claim 5 consists of said heating coils located at any
of
three locations: 1) inside the building's air-handler unit(s), 2) downstream
of the
building's air handler unit(s) in the building's ventilation duct system;
and/or 3) at
the fresh air intake.
9. The application of the method of space-heat delivery claimed in Claim 1 can
also
be utilized for delivery of cooling to the building.

Description

CA 02572418 2006-12-27
1
METHOD OF SUPPLYING HEAT PUMP ENERGY IN BUILDING RETROFITS
The subject of this patent is an innovative, cost effective way to deliver
heat energy,
supplied from heat pumps, to existing buildings.
Background of the Invention
Heat pumps, either air-source or ground source, provide a highly efficient
means of
delivering space heating and cooling. Heat pump technology is well established
and
there are numerous manufacturers and applications of heat pumps in the
Heating,
Ventilation and Air Conditioning (HVAC) industry. Heat pumps use standard
compressor technology commonly found in refrigeration. Depending on the
source,
heat pumps provide from 200% to over 400% energy efficiency. For every unit of
electrical energy used by the heat pump, 2 to 4 times as much heat energy is
produced.
As such, these systems are environmentally desirable as they greatly reduce
building
energy consumption, reduce green house gas emissions, and save the
owner/operator
significant operating costs.
Heat pump technology has progressed substantially in the last twenty years.
The heat
pumps are increasingly efficient and reliable. Given their cost and energy
effectiveness,
they are a desirable system for heating and cooling. Many buildings were built
prior to
the widespread implementation of heat pump technology. Rising energy costs
have
building owner/operators interested in retrofitting existing buildings to have
their heating
and cooling energy supplied by heat pumps.
Description of the Problem
Many buildings are heated with either fuel-fired boilers supplying high-grade
heat to
individual room radiators or electrical resistance heating. The fuel-fired
boiler systems
often operate with heating loop temperatures between 200 F and 160 F and the
radiator fin area is sized accordingly. By contrast, water-to-water or air-to-
water heat
pumps deliver relatively "lower-grade heat, typically on the order of 120 F
to 100 F.
Because of this lower loop temperature, heat pumps cannot directly utilize
building
heating loops designed for fuel-fired boilers. The heat pump exiting water
temperature
is lower than the boilers' return water temperature, so the heat pump does not
deliver
any heat to an existing building heating loop. Furthermore, the radiators in a
boiler
supplied building loop have insufficient fin area to be utilized with the
lower temperature
heat pump supplied water, and therefore the radiators are undersized and
cannot meet
the peak heating loads.
These issues have limited the implementation of heat pump supplied heating in
retrofit
applications. Typical solutions are either to install a second or new heating
system
designed to accommodate the heat pump energy source, or to couple the heat
pump
system to the existing building loop, only providing seasonal building
heating. The
former solution can be very capital intensive, negating cost savings afforded
by the heat
pump. The later solution severely limits the heat pumps' heating potential,
reducing the
energy cost savings offered by the heat pumps.

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Description of Prior Art
There are numerous patents associated with heat pumps and various heat pump
applications. Related patents may include:
. CA 2021842 which provides a means of tempering ventilation air supply with
heat
recovered from exhaust air;
. CA 1102289 which heats mine fresh air utilizing a heat pump recovering heat
from
mine exhaust air; and
. CA 2165673 which provides a means of recovering heat from exhaust air and
supplying that heat (with or without supplemental heat) to the building supply
air.
Summary of the Invention
No prior art has been identified as providing a cost effective solution for
adding or
retrofitting heat-pump supplied energy to an existing building. The nature of
the
invention consists of delivering heat pump derived energy to the building
through its
ventilation system. Specially, heating/cooling coils supplied by the heat pump
are
installed either in, upstream or downstream of the building's air handling
unit(s) (AHUs).
The heat pump supplied coils thereby can provide base-level heating to the
building via
the ventilation air, essentially utilizing the ventilation system as a forced-
air heating
system. The process of adding heat coils and associated piping loop to the
building's
ventilation is a relatively minor retrofit, causing limited building
disturbance and is an
inexpensive retrofit. The additional advantage of this approach is that it
leaves the
building's existing heating system fully intact, functional and unmodified.
This allows the
heat pump(s) to operate independently of the building's existing heating
system and
allows for heating system redundancy in the event of heat supply interruption
in one of
the systems.
Brief Description of the Drawing
Figure 1 illustrates schematically the retrofit application options for heat-
pump supplied
heating coils installed at an air handing unit.
Detailed Description of the Invention
The nature of the invention consists of delivering heat-pump supplied heat
energy
through addition of heating coils to the building's ventilation system: the
heat is then
delivered to the building by heating the ventilation air. Typically, this
arrangement
consists of adding one or several heating coils to the building's Air Handler
Unit(s) as
illustrated on Figure 1. The typical Air Handler Unit (1) takes both building
retumed air
from the building (2) and mixes it with fresh air (3) from the outside before
delivering to
the building (4). The air handier unit typically has an existing heating coil
(5) which
supplies heat from the building's existing heating loop to temper the cold
outside air
before it is delivered to the building. The means of delivering supplemental
heat from
the retrofitted heat pumps is to install one or multiple additional heating
coils in any of
three locations: inside the air handier (6), immediately downstream of the air
handier in
the building's trunk duct (7) or at the fresh air intake (8). If the
supplemental heat coils
are installed at the fresh air intake location (8), the delivery of space heat
to the building
maybe limited if the fresh air dampers are closed. Furthermore, at this
location (position
8), consideration should be given to ensuring freeze protection for the coil
during times
of heat-pump loop shutdown. The added heat coils then have their hot water
delivered

CA 02572418 2006-12-27
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from a separate loop (9) to the new/retrofitted heat pump(s). These
supplemental, or
retrofitted coils thereby deliver space heating energy to the building via the
ventilation
air, raising the ventilation air temperature to meet the building heating
demands. The
size and number of coils will need to be determined on a case-by-case basis
specific to
the building configuration.
In the typical appiication of this invention, the building's base load heating
demand is
supplied from the retrofitted heat pumps and the heat is delivered to the
building via the
ventilation system. Peak and/or specific zone heating is then delivered by the
building's
existing heating system. Under this configuration, the heat pumps will supply
the
majority of the building's heating load, but will not interfere with the
operation of the
building's existing heating system. Control of the heat pump retrofit system
will need to
be determined on a case-by-case basis as every building's systems will be
different.
There may need to be some minor modification of the building's existing
heating and
ventilation control systems to integrate and optimize the retrofitted, heat
pump supplied
heat source.
Note that if the air handier unit incorporates heat recovery from exhaust air
(also known
as a Heat Recovery Ventilator (HRV)), the heat-pump supplied heat coils must
be
installed on the downstream, building side of the HRV. Installing the heat-
pump
supplied heat coils on the cold, fresh air side of the HRV will provided no
heating
benefit.
The retrofitted, heat pump supplied coils can also provide cooling to the
ventilation air
as per the normal appiication.

Representative Drawing