Designing for HVAC and Renewables

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 ….

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 Systems

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.

Basic Objectives provide adequate ventilation for health and comfort (indoor air quality)  fresh air supply (8l/sec.person)  temperature control (T res  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 ( lux)

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, CO 2 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 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 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 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 Systems 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 school The NEW approach

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...

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)

Owner’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 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

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)

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.

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)

Building 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... 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 system design team design process support environment selection implications

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

Technical 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 Assessment Mathematical modelPerformance assessment

Technical Assessment Key outputs from a simulation temperatures heat fluxes air movement humidity power flows Comfort Energy consumption Health and Safety, etc, etc.

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.

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 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

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

Example CHP System Design choice: CHP system Modelling and simulation Assessment: technical feasibility, cost, fuel and CO 2 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 Base Case Design

Appraisal of Options  As above +  advanced glazing  As above +  Solar wall +  lighting control  Base Case  As above +  efficient lighting +  responsive heating

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) report to