designing for hvac and renewables. strategic design of building systems this lecture looks at the...

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


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


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


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


2.a



Fans: 0.00 kWh/m2.a


DHW: 0.00 kWh/m2.a


As above +

advanced glazing


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



2.a



Fans: 0.00 kWh/m2.a


DHW: 0.00 kWh/m2.a


As above +

Solar wall +

lighting control

Base Case


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



2.a



Fans: 0.00 kWh/m2.a


DHW: 0.00 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


2.a



Fans: 0.00 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


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


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]

designing for hvac and renewables. strategic design of building systems this lecture looks at the...

Documents