Transcript 16469- Low Energy Building Design Presentation 2

16469- Low Energy Building Design
Presentation 3- Demand/Supply
Matching
Marc Smeed
Edmund Tsang
Graham Dow
DEMAND REDUCTION
START
CIBSE ‘TYPICAL PRACTICE PRIMARY SCHOOL’
FOSSIL FUELS
164
kWh/m2 p.a
ELECTRICITY
32
kWh/m2 p.a
AIR TIGHT CONSTRUCTION
Assumptions
Heating Period External Temp
Design Internal Temp
= 8.6°C1
= 21°C
Metric
Infiltration Rate (m3/m2h) @50pa
Total ACH
2005 CIBSE Part L Regs.
7.0
0.25
Tight Building
5.0
0.20
Very Tight Building
3.0
0.10
Calculated Heat Loss, per m2 per hour = 4.04W/m2h
Calculated Heat Loss, per m2 per hour = 1.61W/m2h
Saving = (4.04-1.61)/4.04 * 100% = 60%
Energy Saving = 27.2 kWh/m2 p.a.
1. ESP-r data output: (Average external temp for heating season)
DEMAND REDUCTION
CIBSE ‘TYPICAL PRACTICE PRIMARY SCHOOL’
FOSSIL FUELS
AIRTIGHTNESS SAVING
SUB-TOTAL
164
kWh/m2 p.a
27.2
kWh/m2 p.a
136.8
kWh/m2 p.a
Assumptions
External Temp
Design Internal Temp
Exchanger εs
Occupied days per year
Occupied hours per day
Ceiling Height
Total Building Ventilation Rate
HEAT RECOVERY
= 8.6°C1
= 21°C
= 65%2
= 1903
=8
= 3m
= 1.5 ACH
Heat flow rate through sensible heat exchanger4
Occupied hours in the year = 1520
Heat Recovered = 17.7 kWh/m2 p.a.
1. ESP-r data output: (Average external temp for occupied hours)
2. CIBSE Guide F: Table 4.6,p.4-13
3. www.cumbria.gov.uk
4. ASHRAE Handbook 2004: Chapter 44
qs = εs*mmin*Cp*(∆T)
= 65%*(0.00125*1.284)*1.014*11
= 0.0116kW/m2
DEMAND REDUCTION
CIBSE ‘TYPICAL PRACTICE PRIMARY SCHOOL’
164
kWh/m2 p.a
AIRTIGHTNESS SAVING
27.2
kWh/m2 p.a
HEAT RECOVERY
17.7
kWh/m2 p.a
119.1
kWh/m2 p.a
FOSSIL FUELS
SUB-TOTAL
DEMAND REDUCTION
CIBSE ‘TYPICAL PRACTICE PRIMARY SCHOOL’
FOSSIL FUELS
AIRTIGHTNESS SAVING
HEAT RECOVERY
BEMS
SUB-TOTAL
164
27.2
17.7
2nd Sem.
<119.1
kWh/m2 p.a
kWh/m2 p.a
kWh/m2 p.a
kWh/m2 p.a
kWh/m2 p.a
Assumptions
LIGHTING CONTROL
ELECTRICITY
FOSSIL FUELS
21%
79%
1.
Assumptions
LIGHTING CONTROL
LIGHTING = 10/21 % OF ELECTRICAL LOAD = 47% =
15.2kWh/m2p.a.
1.
LIGHTING CONTROL
Occupancy sensors can reduce lighting load by 30-40%1
This can rise to 75% if integrate with PSALI1
Therefore we can assume that we could obtain at least 35% reduction.
35% X 15.2kWh/m2 = 5.33kWh/m2
Energy Saving= 5.33 kWh/m2 p.a.
1. www.advancebuildings.org
DEMAND REDUCTION
CIBSE ‘TYPICAL PRACTICE PRIMARY SCHOOL’
ELECTIRICITY
PSALI / PIR
EFFICIENT LIGHTING
BEMS
LIGHT SHELVING
SUB-TOTAL
32
5.3
2nd Sem.
2nd Sem.
2nd Sem.
<26.7
kWh/m2 p.a
kWh/m2 p.a
kWh/m2 p.a
kWh/m2 p.a
kWh/m2 p.a
kWh/m2 p.a
ENERGY STORAGE
FLYWHEEL
• A rotor is accelerated, maintaining the
energy in the system as inertial energy
• Maximum Power rating of 2000KW for a
multi-cabinet type
• Maximum Power rating of 500KW for a
single-cabinet type
• Stored energy discharges at a
maximum time of 2 minutes
FLYWHEEL- FEASIBILTY
• ADVANTAGES
–
–
–
Flexible
Commercially available
High power outputs
• DISADVANTAGES
–
–
–
Safety concerns
Short discharge times
Expensive
HYDROGEN STORAGE
• The 3 key elements are
• Electrolysis Mechanism
• Hydrogen Storage
• Fuel Cell
• Hydrogen stored via
• Pressurised storage
• Ammonia
• Metal hydrides
FEASIBILITY
• High storage capacity- around
165 KWh /m3
• Only pressurised hydrogen storage is
currently available for building use
• Other storage only commercially
available for vehicles
• Expensive
THERMAL ENERGY STORAGE
TWO TYPES
• Sensible
– A Tank underground, used for heat storage
(25kWh/m^3)
• Latent
– Higher energy density (around 100kWh/m^3)
– Phase change materials (PCM) used where it
solidifies during night then melts during the day
Demand Shifting
Purpose of Demand Shifting
• Demand shifting makes use of storage
so that peaks and troughs of demand
are levelled off
• Requires intelligent forward thinking
• Can be remotely managed system
and use predictions to help shift loads
What's to be gained
• Throttling a CHP system is not required
• Constant power generation can be
attained, decrease maintenance
problems
• Can help incorporate renewable
systems
DEMAND SHIFTING FOR RENEWABLES
• Demand shifting can be used to
create demand when it suits a
renewable supply.
• For Example- Solar works when there
are higher levels of solar intensity- i.e. in
the summer/midday.
Energy
Energy
Electrical
Appliances
(Fuel Cell/CHP)
Heating
Lighting
(Daylight Use)
(Fuel Cell/CHP)
Electrical
Space
Water
Appliances
(None)
(Solar Thermal)
(Fuel Cell/CHP)
Heating
Lighting
(Daylight Use)
(Fuel Cell/CHP)
Space
(Thermal storage/Solar
Thermal Fuel cell/CHP)
Energy
Electrical
Appliances
(Fuel Cell/CHP)
Lighting
(Daylight Use)
(Fuel Cell/CHP)
Heating
Space
(Thermal storage/Solar
Thermal Fuel
cell/CHP)
Water
(Thermal storage/Solar
Thermal Fuel
cell/CHP)
Water
(Thermal storage/Solar
Thermal Fuel cell/CHP)
SHOULD WE DECOUPLE?
FOR
Against
Seen as a flagship project
towards decentralised
supply
Encourage the use of
renewable systems
Why decouple when we
could have the grid as a
backup
It’s a city centre location
any excess electricity could
be sold
Grid Supply could be used
to meet demand peaks
Auxiliary backup system
could over complicate
design
Know where our energy
comes from
Attract more grant money
and better staff
VISION
What is going to be different about our
School?
– A ‘HYDROGEN’ school
– A DECOUPLED school
A NEW approach to school design
Any Questions ?