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Designing for HVAC and Renewables

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... lightweight) infiltration (surface area/volume) Owner s Requirements ... special processes (industrial, commercial) Building Regulations UK building ... – PowerPoint PPT presentation

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Title: Designing for HVAC and Renewables


1
Designing for HVAC and Renewables
2
Strategic Design of Building Systems
  • 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
    .

3
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
4
Building Systems
5
HVAC System Requirements
  • What 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.

6
Basic Objectives
  • provide adequate ventilation for health and
    comfort (indoor air quality)
  • fresh air supply (8l/sec.person)
  • temperature control (Tres ? 17-22C)
  • 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)

7
Buildings 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)

8
Buildings 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

9
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
10
Buildings 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

11
Building 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 .

12
Strategic Design of Environmental Systems
The OLD school
The NEW approach
architect designs building
design team
engineers design services
fabric and systems design evolves together
poorly performing buildings and systems!
better performing systems, less energy used,
smaller environmental impact
13
Strategic 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 ...

14
Building 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)
15
Owners Requirements
  • Owners, developers 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/environ
    mental impact is often low down on the list of
    priorities

16
Building 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

17
Occupants
  • 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)

18
Energy 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.

19
System 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)

20
Building Regulations
  • UK building regulations
  • insulation requirements (Building Regs / SAP)
  • ventilation levels
  • systems, etc.
  • National and Local Planning
  • Building designation (retrofit)
  • Special Location
  • Local regulations (London Energy Strategy)
  • European Regulations (Buildings Performance
    Directive)

21
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 .

22
Selecting/designing a system
selection
support environment
design process
design team
implications
23
Performance 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

24
Technical Assessment
  • simulation enables a design team to make
    informed choices on a likely systems performance
    accounting for the complex interactions between
    the fabric-occupants and systems

25
Technical Assessment
Mathematical model
Performance assessment
26
Technical Assessment
  • Key outputs from a simulation
  • temperatures
  • heat fluxes
  • air movement
  • humidity
  • power flows
  • Comfort
  • Energy consumption
  • Health and Safety, etc, etc.

27
Environmental 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.

28
Environmental Impact
  • 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

29
Environmental 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

30
Costs
  • 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

31
Example CHP System
Design choice CHP system
Modelling and simulation
Assessment technical feasibility, cost, fuel and
CO2 savings
Yes/no
32
Case Study Lighthouse Building, Glasgow
  • 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
33
Base Case Design
  • Diagram or schematic, if appropriate

34
Appraisal of Options
  • Base Case

35
Final Outcome
36
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)
upload report to http//iqsoft.co.in/students/assi
gnment.php
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