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 17-22°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)

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. 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

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 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)

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 system’s 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 Lighthouse Building 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.

33. Base Case Design • Diagram or schematic, if appropriate

34. As above + • advanced glazing • As above + • Solar wall + • lighting control • As above + • efficient lighting + • responsive heating 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) e-mail report to joe@esru.strath.ac.uk