designing for hvac and renewables. strategic design of building systems this lecture looks at the...
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Designing for HVAC and RenewablesDesigning for HVAC and Renewables
Strategic Design of Building Strategic Design of Building SystemsSystems
This lecture looks at the design and assessment of building environmental systems (HVAC).
Also look at some of the new concepts emerging in the built environment:
•distributed generation/renewables integration;
•demand management for better demand-supply matching.
Firstly what are building environmental systems ….
sources: boilers, chillers, electricity supply
distribution: cables, ducts, fans, pumps, piping, etc.
delivery: radiators, underfloor heating, lights, diffusers, etc.
control: thermostats, dampers, valves, timers, PID controllers, etc. environmental system
Building SystemsBuilding Systems
HVAC System RequirementsHVAC System RequirementsWhat are the design requirements for a building and its environmental systems:
• to provide healthy, comfortable environment for the occupants
The operation of the environmental system can be subject to constraints (this will affect the design):
• e.g. at a minimum running cost
• with minimum environmental impact (EBD)
• no constraints*
* this used to be the case and leads to high energy consumption and high costs - the environmental system rectifies problems inherent in a building design - poor fabric, overcrowding, etc.
Basic ObjectivesBasic Objectives • provide adequate ventilation for health and comfort (indoor air quality)
� fresh air supply (8l/sec.person)
� temperature control (Tres 17-22°C)
�contaminant dispersal (safe levels)
• provide adequate acoustic environment (usually related to the operation of ventilation systems)
• provide adequate lighting levels for safety and performance of tasks (150-600lux)
Buildings and EnvironmentBuildings and Environment • There is increasing concern over the environmental impact of buildings (macro and micro).
•The built environment accounts for over 50% of delivered energy (mainly space heat, electricity)
•Energy consumption has consequences: NOx, SOx, CO2 emissions, poor air quality (impact of fossil based CHP?)
• It is the systems in the building which account for the bulk of the energy consumption
•Previously viewed purely only as a consumer of energy this is changing ...(future electrical networks with embedded generation)
Buildings and EnvironmentBuildings and Environment • Now possible to produce much of its own heat and power from energy efficient or “clean” technologies:
•CHP
•Photovoltaics PV
•Micro turbines
•Ducted Wind Turbines
•Fuel Cells
•Heat Pumps - air source and ground source
•Solar thermal/passive solar
sources: boilers, chillers, electricity supply
distribution: cables, ducts, fans, pumps, piping, etc.
delivery: radiators, underfloor heating, lights, diffusers, etc.
control: thermostats, dampers, valves, timers, PID controllers, etc.
Localised generation of heat and power – distributed/ embedded generation
Buildings and EnvironmentBuildings and Environment • It is equally important that the overall demand (energy intensity of buildings is minimised):
• passive solar technology
• well insulated, well maintained fabric
• day lighting, efficient lighting
• well maintained, efficient distribution systems
• natural ventilation
• mechanical ventilation/heat recovery
• energy saving controls
• high efficiency heating and cooling devices
Building & Systems DesignBuilding & Systems Design • The need to satisfy human comfort while consider environmental impact and meet a host of other criteria means that building design is a complex process
• Fundamentally a building is complex, integrated energy system (the possibility of distributed generation and need for reducing demand only makes it more so)
• It will not “work” unless properly designed and analysed
• The majority of buildings in the UK are poorly designed: over specified HVAC plant, poor occupant comfort, high energy consumption, reliant on tight control and system over capacity to accommodate basic design faults
• requires an integrated, team based design process ….
Strategic Design of Environmental Strategic Design of Environmental SystemsSystems
architect designs building
engineers design services
poorly performing buildings and systems!
design team
fabric and systems design evolves together
better performing systems, less energy used, smaller
environmental impact
The OLD schoolThe NEW approach
Strategic DesignStrategic Design
The design of a building takes the following into account:
• site and location (renewables integration)
• energy and other utility supplies (dictated by plant type)
• owner requirements (function, cost)
• occupant characteristics and requirements (comfort, health and plant capacity)
• building regulations (minimum requirements)
• environmental impact and regulations (EC EPD)
ALL of these factors will affect the design and performance ...
Building Site and FormBuilding Site and Form Building location:
warm/cool climate
urban/rural site
available energy resources and services
Building form
building orientation
building form (shallow plan/deep plan)
glazing areas/shading
structure (heavyweight, lightweight)
infiltration (surface area/volume)
Owner’s RequirementsOwner’s Requirements • Owners, developer’s requirements:
• building function
• cost limits
• environmental strategy
•NB distributed generation, renewables integration and energy efficiency, all increase the capital cost of a building
•Very often energy costs are much less than other costs e.g. wages and so energy consumption/environmental impact is often low down on the list of priorities
Building FabricBuilding Fabric • Building category and use:
domestic (cost/ profit margins)
Commercial/ industrial (speculative/custom built, etc.)
• Space usage (kitchen, office, toilet, etc)
• Layout
• Flexibility of use (changes of use in building lifetime)
• Special features:
atria
solar chimneys
sun spaces
OccupantsOccupants
• occupant density (ventilation requirements, cooling/heating requirements)
• occupant activity (design temperatures, ventilation, cooling/heating levels)
• occupant type (children, adults, old/sick)
• occupation of the building (intermittent, 24 hour)
Energy SuppliesEnergy Supplies
• Grid availability, grid connected
• Gas availability (network connection not always available)
• Solid fuel availability
• Other local resource, e.g. district heating, CHP
• Solar resource (geography, climate, site)
• Other resources - wind, biomass, etc.
System RequirementsSystem Requirements• heating and/or cooling
quick response (dynamics - building fabric)
delivery mechanism (convective/radiant/mixed)
• ventilation (mechanical, natural, contaminants)
• humidification/dehumidification and air conditioning
•Lighting (daylighting, task lighting)
•special processes (industrial, commercial)
Building RegulationsBuilding Regulations • UK building regulations:
• insulation requirements (Building Reg’s / SAP)
• ventilation levels
• systems, etc.
• National and Local Planning
• Building designation (retrofit)
• Special Location
• Local regulations (London Energy Strategy)
• European Regulations (Buildings Performance Directive)
Evaluating a design...Evaluating a design...
• the design of for a building and selection of systems and components is an iterative process
• probably the most important evaluation is the performance evaluation
• this is best done looking at all the elements of the building design as they evolve together
• this type of design model requires feedback on the likely performance of a system ….
Selecting/designing a systemSelecting/designing a system
design team design process support environment
selection
implications
Performance EvaluationPerformance Evaluation• an appropriate support environment for the building design process is building environmental simulation
• simulation is the mathematical modelling of a building operating in realistic dynamic conditions
• allows the design team to assess environmental performance (human comfort, energy consumption, emissions, etc.):
•building form and fabric
•orientation and site
•occupancy
•systems (HVAC + RE)
•controls action
Technical AssessmentTechnical Assessment• simulation enables a design team to make informed choices on a likely system’s performance accounting for the complex interactions between the
fabric-occupants and systems
Technical AssessmentTechnical Assessment
Mathematical model Performance assessment
Technical AssessmentTechnical Assessment
•Key outputs from a simulation
•temperatures
•heat fluxes
•air movement
•humidity
•power flows
•Comfort
•Energy consumption
•Health and Safety, etc, etc.
Environmental ImpactEnvironmental Impact• Environmental Impact:
• the quantity of resources used in the construction and running of a system (fossil fuels, metals, plastics)
• the emissions from the system which are harmful to people and the environment
• the ease of disposal and ability to recycle elements of the system
•The selection of the environmental systems will have a significant affect on the environmental impact of the building.
•High Impact:
full air conditioning (heating/cooling humidification, etc)
electric heating (from non-renewable sources)
incandescent feature lighting
Medium Impact:
mechanical ventilation
heating using fossil fuels
fluorescent lighting
Environmental ImpactEnvironmental Impact
Environmental ImpactEnvironmental Impact• Low impact:
solar water heating
natural ventilation*
daylighting*
use of thermal mass*/ thermal insulation*
photovoltaic power production*
combined heat and power
daylight-linked controls
occupancy sensors
energy management systems
* strongly linked to the orientation and design of the building fabric
CostsCosts• Capital cost
• system and installation costs
• Running costs (Whole life costs)
• fuel costs: electricity, gas
• maintenance costs
• High environmental impact systems tend to be high cost systems, e.g. air conditioning has high capital and running costs
• Some Low environmental impact systems have high capital costs e.g. CHP, energy management systems building integrated wind turbines and photovoltaics
Example CHP SystemExample CHP System
Design choice: CHP system
Modelling and simulation
Assessment: technical feasibility, cost, fuel
and CO2 savings
Yes/no
policies being enacted to foster energy efficiency and clean technologies for environmental impact mitigation;
implementation at the local level is problematic;
cities can best respond by - using simulation to appraise options - and establishing databases to appraise replication;aim is to help planners and designers
to match renewable energy resources to reduced demand.
Lighthouse Building
Case Study: Lighthouse Building, Glasgow
• Diagram or schematic, if appropriate
Lighthouse Viewing Gallery Glare Sources (cd/m2)
Version: Base caseContact: ESRUDate: Sep-97
Viewing gallery base case model,double glazing in all windows.No lighting control
Annual Energy Performance
Heating: 118.29kWh/m2.a
Cooling: 0.00kWh/m2.a
Lighting: 100.10kWh/m2.a
Fans: 0.00kWh/m2.a
Small PL: 0.00kWh/m2.a
DHW: 0.00kWh/m2.a
Total: 218.39kWh/m2.a
Maximum Capacity147.06
0.00
25.00
0.00 0.00 0.000
20
40
60
80
100
120
140
160
Heating
Cooling
Lighting
Fans
SPL
DHW
Thermal Comfort
0
10
20
30
40
50
60
70
80
16.0-18.0
18.0-20.0
20.0-22.0
22.0-24.0
24.0-26.0
26.0-28.0
28.0-30.0Resultant Temperature (
oC)
Winter
Spring
Summer
Daylight Availability
0
5
10
15
20
25
0 1 2 3 4 5 6 7 Distance (m)
major
minor
Emissions
0.001
0.01
0.1
1
10
100
1000
CO2 NOx SOx
Heating Lighting
Energy Demand per Unit Time
020406080
100120140160180200
1 3 5 7 9 11 13 15 17 19 21 23 2 4 6 8 10 12 14 16 18 20 22 24 1 3 5 7 9 11 13 15 17 19 21 23
Time (h)
Heating Lighting
Winter SummerTransition
Base Case Design
Energy Demand per Unit Time
020406080
100120140160180200
1 3 5 7 9 11 13 15 17 19 21 23 2 4 6 8 10 12 14 16 18 20 22 24 1 3 5 7 9 11 13 15 17 19 21 23
Time (h)W
/m2
Heating Lighting
Winter SummerTransition
Annual Energy PerformanceHeating: 118.29 kWh/m
2.a
Cooling: 0.00 kWh/m2.a
Lighting: 100.10 kWh/m2.a
Fans: 0.00 kWh/m2.a
Small PL: 0.00 kWh/m2.a
DHW: 0.00 kWh/m2.a
Total: 218.39 kWh/m2.a
Appraisal of Options
Energy Demand per Unit Time
020406080
100120140160180200
1 3 5 7 9 11 13 15 17 19 21 23 2 4 6 8 10 12 14 16 18 20 22 24 1 3 5 7 9 11 13 15 17 19 21 23Time (h)
W/m
2
Heating Lighting
Winter SummerTransit ion
Annual Energy PerformanceHeating: 49.07 kWh/m
2.a
Cooling: 0.00 kWh/m2.a
Lighting: 100.10 kWh/m2.a
Fans: 0.00 kWh/m2.a
Small PL: 0.00 kWh/m2.a
DHW: 0.00 kWh/m2.a
Total: 149.17 kWh/m2.a
As above +
advanced glazing
Energy Demand per Unit Time
020406080
100120140160180200
1 3 5 7 9 11 13 15 17 19 21 23 2 4 6 8 10 12 14 16 18 20 22 24 1 3 5 7 9 11 13 15 17 19 21 23Time (h)
W/m
2
Heating Lighting
Winter SummerTransition
Annual Energy PerformanceHeating: 64.52 kWh/m
2.a
Cooling: 0.00 kWh/m2.a
Lighting: 41.59 kWh/m2.a
Fans: 0.00 kWh/m2.a
Small PL: 0.00 kWh/m2.a
DHW: 0.00 kWh/m2.a
Total: 106.12 kWh/m2.a
As above +
Solar wall +
lighting control
Base Case
Energy Demand per Unit Time
020406080
100120140160180200
1 3 5 7 9 11 13 15 17 19 21 23 2 4 6 8 10 12 14 16 18 20 22 24 1 3 5 7 9 11 13 15 17 19 21 23Time (h)
W/m
2
Heating Lighting
Winter SummerTransition
Annual Energy PerformanceHeating: 48.99 kWh/m
2.a
Cooling: 0.00 kWh/m2.a
Lighting: 19.96 kWh/m2.a
Fans: 0.00 kWh/m2.a
Small PL: 0.00 kWh/m2.a
DHW: 0.00 kWh/m2.a
Total: 68.96 kWh/m2.a
As above +
efficient lighting +
responsive heating
Lighthouse Viewing Gallery Glare Sources (cd/m2)
Version: reference 3 opt 2 + REContact: ESRUDate: Sep-97
Viewing gallery with advancedglazing in all windows.On/off lighting control, EE lighting.TI wall.PV hybrid + ducted wind turbines
Annual Energy PerformanceHeating: 48.99 kWh/m
2.a
Cooling: 0.00 kWh/m2.a
Lighting: 19.96 kWh/m2.a
Fans: 0.00 kWh/m2.a
Total: 68.96 kWh/m2.a
DWT 25.03 kWh/m2.a
PVe 33.79 kWh/m2.a
PVh 40.91 kWh/m2.a
Maximum Capacity
48.13
0.0012.00
41.60
58.40
38.60
0
20
40
60
80
100
120
140
160
Heating
Cooling
Lighting
PVe
PVh
DWT
Thermal Comfort
0
10
20
30
40
50
60
70
80
16.0-18.0 18.0-20.0 20.0-22.0 22.0-24.0 24.0-26.0 26.0-28.0 28.0-30.0Resultant Temperature (oC)
Winter
Spring
Summer
Daylight Availability
0
5
10
15
20
25
0 1 2 3 4 5 6 7 Distance (m)
major
minor
Emissions
0.001
0.01
0.1
1
10
100
1000
CO2 NOx SOx
Heating Lighting
Energy Demand per Unit Time
020
406080
100120140160
180200
1 3 5 7 9 11 13 15 17 19 21 23 2 4 6 8 10 12 14 16 18 20 22 24 1 3 5 7 9 11 13 15 17 19 21 23Time (h)
Heating Lighting
DWT PVe
PVh
Winter SummerTransition
Final Outcome
Assignment Using the internet and other resources find a case study of a low energy building and write a short report on about the systems associated with it. Include the following in the report.
+ Describe the main energy consuming HVAC systems in the building, their function and the types of energy which they use.
+ Mention if renewable or distributed generation systems have been used and describe them.
+ Describe what techniques have been used to minimise energy consumption and try to explain how they work.
(500 words max) e-mail report to [email protected]