Building the business case: worked example WC Lighting in a single-shift factory 50 wks/yr 5 days/wk Improvement measure: introduce PIR control Existing New Number of halogen lamps 8 4 Wattage 50W 50W (no change) Total wattage 400W 200W Operating hours per annum 2,500 50 (visits) x 5/60 x 5 x 50 = 1041 Total kWhpa 1,000 208 Annual Cost at 13p/kWh £130 £27 SAVING £76 per annum Cost of PIR Fitted £70 Simple Payback period 76 / 70 = 11 months k
Building the business case: summary Rationale • Description of the measure • Costs including quotes • Payback • Any other benefits • Any H&S considerations • k
Understanding and controlling your current energy use for space heating k
Types of heat k
What is thermal comfort? Different for every person – Air temperature – Radiant temperature of surfaces – Relative humidity – Air movement – Metabolic heat / activity level – Clothing – Well being k
Personal comfort systems Low power devices provide • heating and cooling Claim up to 50% savings on • heating costs for offices Allow individuals to control their • own thermal-environment k
What are sources of heating? People • Thermal mass • Insolation • IT • Cooling equipment • Process equipment • Heating system • k
Understanding the units Energy is measured in kWh – kilowatt-hour One kWh is one unit on an electricity or gas bill A kilowatt-hour is the energy used by a 1000 watts appliance running for an hour Gas Example Electricity Example A 27kW domestic gas boiler A 1-bar electric fire has a runs at a duty rate of 30% on power rating of 1kW a cold evening so the average power rating is 8.1kW Running for one hour uses 1kWh Running for one hour uses Assuming 13p per kWh 8.1kWh = 13p per hour Assuming 4p per kWh = 32p per hour k
Electric heating Some buildings will use direct resistive heating • either for direct panel heaters or air-conditioning units If you only have one electricity bill then you can make • a quick estimate that 50% of electricity is used for heating and 50% is used for all other electricity needs Some electrically heated sites will have a separate • circuit supply storage heaters on a cheaper rate. k
Worked example Q: Average gas cost for last 3 years is £6,300 – how many kWh of gas is being used if last bill says the unit rate is £0.04? A: Answer gas kWh = [gas cost £] / [unit cost in £/kWh] = £6,300/£0.04 = 157,500 kWh k
Worked example Q: We know that 5 x 2kW electric bar fires are also being used as supplementary heating for 8 hours on 100 days per year. • How much is this costing compared to the gas? • The unit rate for electricity is £0.12/kWh A: kWh of electricity = 10kW x 8 hours x 100 hours = 8000kWh Cost of electricity = 8000kWh x £0.12/kWh = £960 k
External factors Identify other influences on your data: • Cost • Outside temperature or weather conditions e.g. degree days (www.eci.ox.ac.uk/research/energy/degreedays.php#degreeday) k
Benchmarking To allow comparison between buildings it is useful • to compare kWh/m 2 /year (kilowatt-hours per square meter per year) So for a 20m x 50m factory = 1000m 2 • Considering the previous example with 157,500kWh • Consumption per m 2 = 157,500/1000 = • 157.5kWh/m 2 /year k
Benchmarks for heating (CIBSE TM46) Building type Fossil-thermal typical benchmark kWh/m 2 /year General office 120 Large non food shop 170 Bar, pub 350 Hotel 330 Workshop 180 Fitness and Health Centre 440 Storage Facility 150 k
Reduce uncontrolled air leakage Doors • Windows • Other draughts • Check ventilation levels are correct • for current activities k
Reduce uncontrolled air leakage Consider LEV (local extract ventilation) for dusty or fume • filled environments to reduce heat losses k
Consider mechanical heat recovery Air-to-Air heat exchangers can save up to 50% of heating consumption • k
Heating distribution and control k
What do we mean by heat distribution? The system that delivers heat from source to • point of use Usually ‘wet system’ with radiators • Or air source heat pump • Offers good potential for savings via improved • controls k
Insulate pipework • – In plant rooms (easy fix velcro attachments are available for awkward flanges and bends) – Consider insulating distribution pipework if it does not contribute useful heat Keep space around space heaters free • – Avoid files, desks and furniture up against heaters – Leave 15cm between radiators and furniture Record your heating system settings • – Use a simple record sheet to record date and change made – Put dates in the diary (clock changes), Xmas holidays to change settings as needed k
Warm air distribution systems May be HVAC system with gas boiler or ASHP • – Some HVAC systems can be adapted to make use of free cooling (cold outside air) and excess heat internal to the buildings (e.g. server rooms) – Consult a specialist Consider VSDs (Variable Speed Drives) for HVAC and circulation • pumps Ensure a dead band of 4 degrees C is set between heating and • cooling k
Typical heating controls Time clocks • System thermostat • Localised thermostats such as thermostatic radiator valves (TRVs) • Zone controls (BEMS) • k
Types of time control Time clock • – Set start and finish times each day 7 day timer • – Set for earlier start on Monday morning Optimised heating controller • – Uses inside and outside temperature sensors – Learns your building heat up time for different temperatures – Switches on as late as possible k
Switch your heating off early • – Many buildings store heat effectively – People and IT can maintain the building temperature from mid-afternoon – Try moving your switch off time back an hour Consider hot-desking • – Heat from occupants is concentrated in one area – Switch off heating earlier in un-occupied areas Make sure colleagues understand controls • k
Set appropriate temperatures • – Office / low activity 20 ° C – Workshop / high activity 16-18 ° C – Turning down setpoint by 1 ° C could save circa 8% Locate thermostats carefully • – Not near doors – Not in sun k
Control heat gains In shops • – Large heat gains from display lighting and refrigeration In offices • – From occupants and electrical equipment In factories • – From processes such as cooking, welding In many lightweight buildings • – Solar gains through thin walls and glazing k
De-stratification fans Useful for high ceiling premises with a large variation • in temperature with height and a reasonably well insulated and air tight building k
Interlocked heating controls • Fast opening roller-shutter doors • Air curtains • Flexible doors • k
Boiler replacement and fuel switching k
Fuel switching Consider switching if you are using a high price • fuel such as oil (but has reduced recently), LPG or electricity (day tariff). Alternatives are • Natural gas • Biomass • Heat Pumps – Air, Ground or Water – source. • k
Biomass Burns wood in one of three forms • Logs (Large scale, low fuel costs) • Chips • Pellets (Smaller scale, higher fuel • cost) High level of automation • Very low carbon factor • If sustainable fuel! • k
Biomass – free procurement guide www.resourceefficientscotland.com/resource/ procurement-support-how-carry-out-successful-biomass-heating-project k
Heat Pumps Air Source – coefficient of performance (COP) • of 2 to 3 Ground Source – COP of 3 to 5 • Move heat rather than create it • k
Renewable Heat Incentive Government funded subsidy for renewable heat projects • Paid quarterly per kWh of heat produced • Rate fixed at commissioning and then paid for 20 years • (index linked) Helps pay for higher costs of renewable equipment • Typical paybacks around 8-12 years • k
Radiant Heat Heat surfaces not space • k
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Understanding and controlling your current energy use for lighting k
How does lighting work? Type Operation Efficiency Lifetime (Lumens per in hours Watt) Incandescent/ Electric resistance heats filament to ~2500 15 1000 Tungsten degrees C in inert gas. Fluorescent High voltage used to ionise mercury into a 50-100 10,000 – Lighting vapour. This causes electrons to emit UV 20,000 photons which is converted to visible light by phosphor coating on the inside of the tube LED Voltage applied to a semiconductor junction Up to 100* 40,000 emits photons k
Types of lighting Incandescent (Tungsten) CFL Halogen Fluorescent T12: 38mm 1.5” (2p) T8: 25mm 1” (1p) T5: 16mm 5 / 8 ” (5p) k
Types of lighting 2 LEDs k
Types of lighting 3 Discharge Lighting SON / Sodium Vapour Lamp Metal Halide k
Characteristics of lighting k
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