Lighting for Dairy Farms

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Improving the Welsh Dairy Supply Chain

Lighting for Dairy Farms

www.ddc-wales.co.uk

Gelli Aur Lighting for Dairy Farms A5_13605 Practical sheep breeding 13/07/2012 12:19 Page 2

Dairy Development Centre Gelli Aur Carmarthen Carmarthenshire SA32 8NJ Telephone: 01554 748570 E-mail: [email protected] www.ddc-wales.co.uk July 2012 The Dairy Development Centre (DDC) acknowledges the contribution made by Farm Energy to the technical content of this booklet. This project has received funding through the Rural Development Plan for Wales 2007-2013 which is funded by the Welsh Government and the European Agricultural Fund for Rural Development. No part of this publication may be reproduced or transmitted in any form by any means without the prior written consent of the Dairy Development Centre. Whilst all reasonable care has been taken in its preparation, no warranty is given as to its accuracy, no liability accepted for any loss or damage caused by reliance upon any statement in or omission from this publication.

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Contents

The requirement for light

4

Properties of light

4

Animal performance

6

Tasks and lighting requirement

6

How to get light

7

Lighting types

8

Control

10

Lighting design

12

Lighting for Dairy Farms

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The requirement for light Light is required for both stockmen and stock. There are minimum light level requirements for both general observing and animal welfare inspections. Stockmen sometimes require enhanced lighting levels for more visually demanding tasks. In such cases higher light levels may need to be provided in certain areas during a specific time. A number of studies have shown that dairy cows which are given a longer photoperiod will increase milk production by between 5 – 16% (an 8% response being typical).

Properties of light There are a few important characteristics of light which are worth considering when a lighting system is being designed. Lighting level This is measured in lux. Lux is not a ‘linear scale’ so a doubled lux level does not appear as twice the brightness to the eye. In fact you have to increase lux levels by 4 to double the perceived light level or by 16 to double it again.

Condition Bright Sunlight

80,000

Overcast day

5,000

Bad light stops play

1,000

Modern office Twilight Road lighting

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Light level (Lux)

500 10 5

Full moon

0.2

Starlight

0.02

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Lighting colour rendering The degree to which light from different sources accurately renders colour is known as the colour rendering index (Ra) with a maximum level of Ra 100. Best rendering is from natural daylight and tungsten light. At the other end of the scale is low pressure sodium light (the yellow light used for street lighting) which has an index of just Ra 20. Colour rendering is important when it’s necessary to distinguish one colour from the next - for veterinary tasks for instance. Uniformity Lighting uniformity is generally not a critical thing for most dairy buildings other than in the milking parlour itself. Using a larger number of small lamps as opposed to fewer large ones will give best uniformity. Shadows Shadows most frequently occur when a small number of high power lamps are used. Shadows can be minimised by using lamps with a large emitting area – like long fluorescent lamps and by employing a larger number of smaller wattage lamps. The performance of a lighting system is often a compromise between the installation of a large array of the most desirable lamps and cost. Fewer larger lamps will always tend to be cheaper to install both in terms of wiring and capital equipment, but uniformity and the production of shadows will be worse. The following illustration shows the effect of the type of lighting and the number of luminaires (light fittings) on the light uniformity.

Fewer number of large lamps – poorer uniformity and greater shadowing effect

Greater number of small lamps – increased uniformity and less shadowing effect

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Animal performance The effect of the lighting period on milk yield has been the subject of a number of studies in Europe, United States and Canada over the last 30 years. A consensus seems to show that milk output and feed intake of lactating cows is highest with light periods of 16 to 18 hours per day and with a lighting level of at least 170 to 200 lux. On average it is expected that cows housed under artificial lighting will produce an average of 2 litres/day more than control animals utilising natural photoperiod only. Tasks and lighting requirement The following table gives some guidance on lighting levels and desirable light properties for different areas of a dairy enterprise. There are no definitive standards in this area, so this table contains figures derived from practical experience and from similar practical references.

Applications

Lux level required

Colour rendering

Uniformity

Control

Comments

Cubicle and feeding area

170 to 200 lux for photo period yield effect, 50 lux for general

Low to medium

Medium

Timed, with light level sensing. Fluorescents can use light level driven dimming

High pressure sodium, metal halide lights or multiple fluorescent fittings Fluorescent lights will punch light through the mass of pipes and fittings and give even shadow-less light.

Milking area

500 lux for pit

Good

Very good

Timed with manual override

Collection yard

50 lux

Low to medium

Medium

Timed with manual override

High pressure sodium or metal halide lights

Bulk tank area

200 lux

Good

Medium

Proximity

Fluorescent lights are most commonly used

Outside areas

20 lux

Low to medium

Low

Timed/light level

High pressure sodium or metal halide lights are the best compromise between cost and performance

Office

300 - 500 lux

Good

Good

Proximity

Fluorescent lights are most commonly used

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How to get light Light can be provided naturally or artificially. Natural lighting Natural lighting can make a very big contribution to dairy buildings, both in cubicle housing and for parlours and other areas. Providing 10 - 15% of the total roof area as roof-lights will be enough to provide between 100 and 500 lux through natural lighting depending on the time of day and year. The key to sustaining this is to maintain the cleanliness of the roof-lights. Transparent wall sections are also effective. Naturally lit buildings need to be well ventilated to counteract the effects of heat build up from solar gain.

Artificial lighting Even with the best natural lighting resource, artificial light has to be used to guarantee light in all conditions, depending on time of day and time of year. But of course artificial light is costly to provide, so it’s always best to make the most of natural light and use artificial light to provide the remainder.

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Lighting types There are a wide range of lighting sources to choose from and each type has its own unique set of characteristics. These include: capital cost, efficiency, longevity, colour appearance, colour temperature, shadow potential, and start up time. It’s important to try to consider the relevance of these when choosing the right lamp type. The most popular types of lighting are shown in the following table, all of which can be effectively used in dairy lighting. Category

Type

Overall luminous efficacy (lm/W)

Overall luminous efficiency (%)

Incandescent

100–200 W Tungsten incandescent (230 V)

14

2.1%

100–200–500 W Tungsten halogen (230 V)

17

2.5%

7 W LED to 15W

55.1–81.9

8 - 12%

7 W LED PAR20 (110-230 V)

60.0

8.8%

Theoretical limit

260.0–300.0

38.1–43.9%

T12 tube with magnetic ballast

60

9%

9–32 W compact fluorescent

46–75

8–11.45%

T5 or T8 tube with electronic ballast

80–100

12–15%

Metal halide lamp

65–115

9.5–17%

High pressure sodium lamp

85–150

12–22%

Low pressure sodium lamp

100–200

15–29%

Light-emitting diode

Fluorescent

Gas discharge

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Colour appearance /rendering

Life (hours)

Comments

White /good

1000

Cheap to buy. Expensive to run. Being phased out for small bulbs.

White /good

2000

Cheap to buy and widely used for yards. Expensive to run if operated for long hours. Best used on a proximity sensor.

White /good

50,000

White /good

50,000

White /good

50,000

White /good

8,000

Old type of tube 1½ inches in diameter – being phased out.

White /good

5,000

Natural replacement for tungsten bulbs with lots of new designs, some dimmable.

White /good

15,000

Workhorse for commercial buildings where good quality low shadow efficient light is needed. Newer ballast types more efficient and dimmable.

White /good

15,000

White appearance. Alternative to sodium. Takes a few minutes to warm up.

Yellow/ medium

20,000

Yellow appearance. The most popular light for wide span buildings. Takes a few minutes to warm up.

Harsh yellow/ bad

25,000

Monochromatic yellow light. Very basic light for use outside. Takes a few minutes to warm up.

Currently very expensive to buy and less efficient than most discharge lamps. Newer types promise high efficiencies. Very directional. Most efficient at cold temperatures.

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Control Good lighting control is the key to managing the use of light and to ensure that the correct light is provided in the right place and at the right time. Automatic lighting controls are based either on one, or a combination of these three factors: • • •

Movement Time Ambient light

Movement Sensors Movement Sensors include passive infra-red (PIR), ultrasonic and microwave. PIR’s are the most common and cheapest sensor, although they are quite coarse in operation. At the other extreme microwaves are very sensitive and will react to the slightest movement. Some of the best control systems use PIR’s to switch lights on and a microwave sensor to maintain the on-state. Timers Timers are either time switches or time delay devices. Time switches usually have a 24 hour cycle or a 24 hour, 7 day cycle. The latter is useful where operational times change on certain days of the week. The best timers have a battery reserve so they continue to keep time if the electricity supply fails. You can use ‘solar’ time switches to control outside lights. These are preprogrammed to allow for the change in day length which occurs throughout the year.

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Delay devices Delay devices are preset to switch off lights after they've been switched on. They are used for areas of temporary occupation – like walk-ways or toilets – where lights only need to be on for prescribed short periods.

Ambient light sensors Ambient light sensors in their simplest form, switch lights on and off as the ambient light levels cross a particular value. They are positioned outside to sense ambient lighting conditions. Light sensors can also be used to maintain lighting at a particular level inside a building where some natural lighting is available. They signal to the lighting system to increase the lighting output incrementally to supplement or replace daylight. Hybrid systems using these techniques can be used to obtain the necessary functionality. So for instance, an ambient light sensor may be used to switch lights on as daylight fades, and a time switch used to switch lights off in the late evening when high lighting levels are not required by staff.

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Lighting design Lighting design is important as it will determine the performance of the lighting for the life of this system. It’s therefore worth getting some professional advice to get the lighting right. The preceding sections have covered the issues of lighting level, light uniformity, shadows, colour, and control - all these things must be considered in the design process. A few additional points may need to be examined: •

Consider the way lighting is used on an everyday basis. Where is the most suitable area for the switches to be located? Is it possible to get different lighting levels by simply grouping and switching the lights on/off in clusters?

•

Are the lights in a position where they can be easily cleaned and where the bulbs can be safely changed?

•

Consider reflectivity off roofs and walls. Colouring surfaces white or a light colour can increase the lighting level dramatically.

•

Fittings in most cases will have to be water and dust proof. Make sure the ones you choose are up to standard.

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