A G R I C U LT U R A L A N D F O O D S C I E N C E M. Rajaniemi & J. Ahokas (2015) 24: 10–23 10 Direct energy consumption and CO 2 emissions in a Finnish broiler house – a case study Mari Rajaniemi and Jukka Ahokas University of Helsinki, Department of Agricultural Sciences, P.O. Box 28, 00014 University of Helsinki, Finland e-mail: mari.rajaniemi@helsinki.fi Direct energy (electricity and heating) consumption was measured from one broiler house in southern Finland. CO 2 emissions were also calculated. Six broiler flocks were reared per year with an average of 26 000 birds per flock. Heating constituted the major energy input, averaging 1.3 kWh kg-1 of carcass weight. It varied greatly between sea- sons and was highest during the cold period. Using renewable energy for heating remarkably reduces CO 2 emissions compared to fossil energy. Electricity consumption averaged 0.08 kWh kg-1 of carcass weight. The greatest energy saving potential can be found in heating. CO 2 emissions can be lowered to similar levels as in warmer countries by using biofuels for heating. Ventilation control is one possibility for direct energy savings in broiler production. Feed production is one of the key elements when total energy consumption is considered. Key words: broiler production, CO 2 emissions, energy consumption, energy measurement, energy efficiency Introduction Broilers are reared on approximately 190 farms in Finland (Siipikarjaliitto 2010). Most of these farms are cen- tered regionally in the proximity of slaughterhouses (Harrinkari and Raukola 2009). Production is highly spe- cialized and based on contracts between farmers and slaughterhouses. An all-in all-out system is used in Finn- ish broiler production. In this system all broiler houses on the same farm are concurrently empty. The aim is to guarantee high production hygiene. Birds arrive on a farm at a few hours of age and weighing approximate- ly 35–45 g. Broiler rearing periods vary from 32 to 39 days. During the rearing period birds gain from 1.3 kg to 1.9 kg of carcass weight. The average broiler carcass weight was 1.6 kg in 2012 (Tike 2013a). Finnish broil- er houses are typically highly automated, fully enclosed, insulated and mainly concrete element-structured buildings (Harrinkari and Raukola 2009). Heating is needed year-round to ensure the recommended temper- ature and relative humidity for broiler houses. Electricity is used mainly for ventilation, lighting and feeding. One of the European Union’s (EU) targets is a 20% reduction in greenhouse gas (GHG) emissions by 2020 compared to levels in 1990 (EC 2009, TEM 2013). In the Finnish agriculture sector this means a 13% reduction compared to levels in 2005 (TEM 2008). As part of this target the EU will increase its renewable energy use. The Finnish target is to increase final renewable energy usage from 28.5% in 2005 up to 38% in 2020 (EC 2009, TEM 2013). The EU is also obligated to increase energy efficiency by 20% by 2020 compared to projections made in 2007 (EU 2012, TEM 2013). A voluntary energy programme for farms exists in Finland. The aims of this programme are to increase renewable energy usage and energy usage efficiency in agriculture (Government regulation 2009) and to increase the energy efficiency of participant farms by 9% by 2016 (Government regulation 2009, EU 2012). Approximately 10.4 TWh of direct energy was consumed by the Finnish agriculture and horticulture sector in 2010 (Tike 2012). This is approximately 3% of the total direct energy consumption of the country (Tike 2013b). Wood is the largest direct energy input on poultry farms followed by oil and peat (Tike 2012). Approximately 65% of the total direct energy input of poultry farms therefore comes from renewable energy. An increasing number of Finn- ish broiler farms use renewable energy for heating, but fossil energy is still used on many broiler farms around the world (e.g. Baughman and Parkhurst 1977, Liang et al. 2009). Indirect energy is used mainly as feed, which is the largest energy input of broiler houses (e.g. Baughman and Parkhurst 1977, agrEE 2012). Studies have shown (Ahokas et al. 2014) that it is possible to considerably save en- ergy in feed production e.g. with more efficient production methods and nutrient recycling. Heating is the largest direct energy input of broiler houses (Baughman and Parkhurst 1977, Barber et al. 1989, Katajajuuri et al. 2006, Hörndahl 2008). It is also the greatest CO 2 emission source of broiler houses when fossil fuel is used for heating. Biofuel usage for heating has increased in broiler production e.g. in Finland and Sweden during the last years (e.g. Sonesson et al. 2009). Biofuel combustion is traditionally assumed to be CO 2 neutral. Biofuel combustion hence reduces CO 2 emissions compared to the combustion of fossil fuels. The biofuel production chain causes emissions (Mäkinen et al. 2006), but that portion of the total GHG emissions is minor. Manuscript received October 2014 A G R I C U LT U R A L A N D F O O D S C I E N C E M. Rajaniemi & J. Ahokas (2015) 24: 10–23 11 Climate, bird mass, house type and insulation greatly affect heating energy consumption. It is higher during cold seasons than warm seasons due to higher heat loss from buildings and ventilation (e.g. Bokkers et al. 2010). En- ergy demand is lower at the beginning of the rearing period due to the low ventilation rate (Mannfors and Hau- tala 2011). Some previous studies (Baughman and Parkhurst 1977, Liang et al. 2009) showed that insulated and enclosed broiler houses (environmental houses) use less heating energy than curtain side-wall houses (Table 1). However, electricity consumption is usually higher in environmental houses due to artificial lighting and mechani- cal ventilation (e.g. Baughman and Parkhurst 1977, Liang et al. 2009). Several studies (Baughman and Parkhurst 1977, Katajajuuri et al. 2006, Hörndahl 2008, Liang et al. 2009) showed that the electricity consumption of broiler houses is minor compared to that of heating. Ventilation and lighting are usually the biggest electricity consum- ers (Hörndahl 2008, Liang et al. 2009, agrEE 2012). Heating and electric energy consumption vary in different studies and countries (Table 1). Kivinen et al. (2013) cal- culated the theoretical heating energy consumption of one broiler house (1 600 m2, with space for 28 000 birds). In their study the biggest heat losses occurred through ventilation. Greatest energy savings could be found in heat recovery from the exhaust air. Kivinen et al. (2013) also noticed that controlling ventilation CO 2 levels could save energy. Energy can be conserved e.g. by decreasing the ventilation rate during dark cycles, when broilers are not active. Katajajuuri et al. (2006) studied the heating energy consumption of 16 broiler houses in Finland. They also calculated the theoretical heating energy demand of a broiler house, which was found to be lower than the heat- ing energy consumption of practical broiler farms. Studies by Katajajuuri et al. (2006) and Kivinen et al. (2013) in- dicate that the theoretical heating energy consumption was lower than the heating energy consumption in prac- tical conditions on farms. Table 1. Electricity and heating energy consumptions in broiler houses. Heating kWh kg-1 of carcass weight Electricity kWh kg-1 of carcass weight Remarks Reference 0.701 0.121 Measured energy consumption of the broiler house in Sweden. Hörndahl (2008) 0.75 - Theoretical energy consumption in Helsinki, Finland. Kivinen et al. (2013) 0.95 - Theoretical energy consumption in Jyväskylä, Finland. Kivinen et al. (2013) 1.17 - Theoretical energy consumption in Finland. Katajajuuri et al. (2006) 1.31 (varied between 0.94 –1.64) 0.19 (varied between 0.08– 0.35) Consumption was based on interviews and complementary questions made to 16 broiler farms in Finland. Katajajuuri et al. (2006) 0.531,2 0.141 Four enclosed, insulated houses in Northwest Arkansas, USA. Liang et al. (2009) 0.621,2 0.111 Fo u r o p e n - c u r ta i n h o u s e s i n N o r t hwe st Arkansas, USA. Liang et al. (2009) 0.55–3.471 0.17–0.261 Conventional house3) in North Carolina, USA. Baughman and Parkhurst (1977) 0.34–1.851 0.51–0.571 Environmental house4) in North Carolina, USA. Baughman and Parkhurst (1977) 1 Energy consumption per market weight converted to energy consumption per carcass weight using carcass-% of 74. 2 Heating energy was originally presented as litres of liquefied petroleum gas (LPG). It is converted to kWh using the heating value 25 kWh m-3 of LPG and a gas-liquid -ratio of 240:1. 3 Broiler house that is converted to drop-curtain side walls with no insulation or mechanical ventilation. 4 Broiler house that is enclosed and insulated and has mechanical ventilation. Broiler house heat balance can be calculated from heat flows within the building (Fig. 1). When room tempera- ture is higher than the ambient temperature, heat flows from the building to its surroundings. Heat is conducted through the walls, ceiling and floor. A G R I C U LT U R A L A N D F O O D S C I E N C E M. Rajaniemi & J. Ahokas (2015) 24: 10–23 12 The heat flow power depends on structural thermal conductivity (U-value), structure area (A) and structure tem- perature difference (∆T s ) between the inside and outside surfaces (Eq. 1). scond TAUP ∆⋅⋅= (1) P cond heat conductance U structural thermal conductivity A structure area ∆T s temperature difference between inside and outside surfaces Surface temperatures in the building are not the same as indoor and outdoor temperatures. An air boundary layer occurs on the surfaces, and this also has an insulating effect. The U-values of the boundary layers depend on radia- tion, surface air speed (wind) and surface properties. If the walls have effective heat insulation, then the boundary layers only have a minor effect, but this has to be taken into account with poor heat insulation. The heat flow in convection is caused by ventilation. The ventilation rate must be high enough to insure a proper microclimate and animal welfare. If ventilation rate is high compared to microclimate requirements then energy is lost with convection. The heat power of ventilated convection (P conv ) can be calculated with the air mass flow (q m ), specific heat capacity of air (c a ) and the temperature difference of indoor and outdoor air temperatures (∆T a ), Eq. (2). Ventilation inlet Ventilation outlet, Pconv= heat convection Ph = Heating Pcondc = Ceiling heat conductance PB = Broiler heat production Pcondf = Floor heat conductance Pcondw = Wall heat conductance Fig. 1. Heat flows in a broiler house. A G R I C U LT U R A L A N D F O O D S C I E N C E M. Rajaniemi & J. Ahokas (2015) 24: 10–23 13 aamconv TcqP ∆⋅⋅= (2) P conv heat convection q m air mass flow c a specific heat capacity of air ∆T a temperature difference of indoor and outdoor air temperatures The heating power (P h ) of the building can be derived from its heat balance, Eq. (3). This depends on the building`s heat losses and the heat production of the animals. Radiation heat power is not included here because broiler buildings in Finland do not have windows. Radiation however has an effect on outdoor surface temperatures, and in this way it also affects heat conduction. (3) P h heating power P cond heat conductance P conv heat convection P bs broiler-sensible heat production U structural thermal conductivity A area ∆T s structure temperature difference between inside and outside surfaces q m air mass flow c a specific heat capacity of air ∆T a temperature difference of indoor and outdoor air temperatures Broiler-sensible heat production can be calculated using the CIGR method (CIGR 2002), Eq. (4). According to this, the sensible heat power depends on broiler mass and temperature. Broiler house temperature is regulated ac- cording to broiler mass and the power increases with increasing mass heat. (4) P bs broiler-sensible heat production m broiler mass t temperature °C Figure 2 shows an example of how heating power demand changes when outdoor temperature and broiler mass change. Large amounts of heating power are needed when the weather is cold and the broilers are old. The larg- est heat power goes to heating the ventilated air, the requirement for which increases as the birds grow. [ ]2475,0 1028.2))20(020,01(61.062.10 ttmPbs −⋅−−⋅+⋅⋅⋅= Fig. 2. Example of heating power demand during the rearing period of a broiler flock with different ambient temperatures and broiler weights. 27 000 birds with a density of 17 birds m-2 and with recommended ventilation rates and heat insulation materials (MMM- RMO 2001). ∑∑ −∆⋅⋅+∆⋅⋅=−+= bsaamsbsconvcondh PTcqTAUPPPP A G R I C U LT U R A L A N D F O O D S C I E N C E M. Rajaniemi & J. Ahokas (2015) 24: 10–23 14 Figure 3 shows an example of the heating losses in the case presented in Figure 2. Heat is lost mainly through ventilation. Heat conduction losses are small compared to this. With young broilers the ventilation rate is low and heat losses through the walls, ceiling and floor are dominating. Beef and milk production causes the highest GHG emissions of the EU livestock sector (Lesschen et al. 2011, Weis and Leip 2012). GHG emissions per kg of beef are multiple compared to emissions per kg of poultry meat (Table 2). Higher emissions produced by ruminants are caused mainly by higher CH 4 and N 2 O emissions (Weis and Leip 2012). Poultry also has a better feed conversion ratio (kg feed kg-1 product) than beef (Pimentel 1980, Lesschen et al. 2011). Table 2. GHG emissions of beef and poultry meat. GHG emissions of beef, kg CO 2-eq kg-1 of beef GHG emissions of poultry meat, kg CO 2-eq kg-1 of poultry Reference 28.7 3.6 Weidema et al. 2008 22.6 1.6 Lesschen et al. 2011 21–28 5–7 Weis and Leip. 2012 Weis and Leip (2010, 2012) have calculated the GHG emissions of poultry meat for 27 EU member states (EU- 27) using the CAPRI (Common Agricultural Policy Regionalised Impact) model, while Lesschen et al. (2011) have used the MITERRA-Europe model and Weidema et al. (2008) the LCA (life cycle assessment) system mod- el. Figure 4 shows the total GHG emissions per kg of poultry meat in the EU-27 countries. According to Weis and Leip (2012) the main causes of GHG emissions (in poultry meat production in the EU-27) are land use and land use change (LULUC) (50%) and energy use (28%). LULUC included the following emission sources: soil cultivation (CO 2 ), carbon stock changes (CO 2 ), biomass burning (CH 4 , N 2 O) and emissions or removals of pastures, croplands and grasslands (CO 2 ). EU-27 GHG emissions vary between 3.3–17.8 kg CO 2-eq kg-1 of poul- try meat, with levels highest in Latvia and lowest in Ireland (Weis and Leip 2012). Emissions averaged 4.9 kg CO 2-eq kg-1 of poultry meat in the EU-27 countries (approximately 10 kg CO 2-eq kg-1 of poultry meat in Finland). 0 50 100 150 200 250 300 350 400 450 500 -32 -26 -22 -18 -14 -10 -6 -2 2 6 10 14 18 22 26 Po w er k W Outdoor temperature °C Walls Windows and doors Ceiling Floor Ventilation Fig. 3. Example of building heat losses when broiler mass is 1.5 kg. A G R I C U LT U R A L A N D F O O D S C I E N C E M. Rajaniemi & J. Ahokas (2015) 24: 10–23 15 GHG emissions per kg of poultry meat were the second highest in Finland compared to other EU-27 countries. The main reason for this was the higher emissions from land use (high share of organic soils in Finland). CO 2 emis- sions from energy use in Finland were approximately 1.5 kg CO 2-eq kg-1 of poultry meat. This was higher than the average emission (1.4 kg CO 2-eq kg-1 of poultry meat) in the EU-27 countries. The reason behind this is probably that more heating is needed in broiler houses in Finland than in other EU-27 countries. Our study focused on direct energy consumption and it´s CO 2 emissions in a modern broiler house. Direct energy consumption includes electricity and heating energy consumption. The aims of our study were 1) to investigate the heating and electric energy consumption of a broiler house 2) to identify the division of direct energy con- sumption inside a broiler house and 3) to explore the CO 2 emissions of combustion and electricity use when dif- ferent fuel sources are utilised. Material and methods Electricity and heating energy consumption were measured in one insulated (wall U-value 0.3 W m-2 K-1) concrete element broiler house located in southern Finland. The broiler house had two identical and fully enclosed rearing sections. The dimensions of one section were: height 3.5 m, width 19.8 m and length 81.4 m. The floor area is 1 615 m2 and the volume 5 655 m3. The broiler house was built in 2008. Energy consumption was measured from one rearing section (later referred to as broiler house), which constitutes half of the building. Information con- cerning production was collected from every broiler flock: feed and water consumption, number of birds, dead birds and carcass weight (a carcass weight of 73% of a live bird’s weight was used in the analyses [Government regulation 2011]). Ross breed broilers arrived at the broiler house at the age of a few hours and their weight was 35–45 g. The birds gained a carcass weight of 1.8 kg (live weight of 2.46 kg) within 38 days. Six flocks were reared per year, with an aver- age 26 000 slaughter birds per flock. An all-in all-out production system was applied. A down time of approximately 2–5 weeks was implemented after each rearing period. During this time the house was cleaned and disinfected. The broiler house had a central heating system and renewable energy (wood chips) was mainly used as fuel. There were two pipe radiators on the walls and four water to air heat radiators equipped with fans in the middle of the house. The heating energy consumption of both these systems was measured. The electricity consumption of four radiators with fans was included in a part of the miscellaneous electricity consumption. Heating was controlled by four thermostats, which measured the average temperature of the house. The house was pre-heated to 33 °C before the birds arrived. The temperature was decreased stepwise to 21 °C by the end of the rearing period. The broiler house needed heating year-round except on the hottest summer days. Fig. 4. Total GHG emissions per kg of poultry meat in the EU-27 countries. The figure is made from data by Weis and Leip (2010). 0 2 4 6 8 10 12 14 16 18 20 BL D K D E EL ES FR IR IT N L AT P T SE F I U K CY CZ EE H U LT LV M T PL S I SK BG RO EU G H G e m is si on s kg C O 2- eq kg -1 o f p ou ltr y m ea t EU member state CO2 LULUC2 CO2 Energy N2O CH4 A G R I C U LT U R A L A N D F O O D S C I E N C E M. Rajaniemi & J. Ahokas (2015) 24: 10–23 16 The lighting consisted of 84 fluorescent tube lights (nominal power 36 W light-1). The lights were brightest during the first days and were dimmed stepwise after two days. The lighting programme mainly began on day three. It included at least six hours of dark and 18 hours of light. The dark cycle was divided into two parts. The house was equipped with a negative pressure ventilation system. The system included three on/off ventilation fans (diameter 0.80 m, nominal power 1.09 kW) in the ceiling, two ceiling fans (diameter 0.80 m, nominal pow- er 0.91 kW) with adjustable speed and four belt-driven tunnel ventilation fans (diameter 1.27 m, nominal power 1.10 kW) in the gable. Ventilation inlets (12 pieces) were located in two lines in the ceiling. Ventilation control was based on the expected rearing curve, bird weight, humidity and temperature. Tunnel ventilation fans were used mainly during the summertime when extra cooling was needed. Heating energy consumption was measured from May 2011 to May 2013. Data was collected from 12 broiler flocks. Heating energy consumption was measured using an energy meter. Heat losses in the heat canals and the furnace efficiency were were not considered. Electricity consumption measurements were divided into three groups: total electricity consumption, ventilation and lighting. When the ventilation and lighting energy were subtracted from the total electricity consumption, the remaining part was denoted as miscellaneous energy consumption. This included e.g. an automatic feeding system and fans of four heat radiators. Electricity consumption of the broiler house was measured from May 2012 to May 2013. The energy consumption of the tunnel ventilation fans and lights was measured at 20-minute inter- vals and at 10-minute intervals for adjustable and on/off fans. Indoor- and outdoor temperatures were also measured. Outdoor and indoor temperatures were measured at 20- and 30-minute intervals, respectively. Table 3 shows the instrumentation used for the measurements. Data was collected with a data logger and uploaded and analysed after each rearing period. Energy consumption was calculated as kWh per 1 kg of carcass weight and as kWh per broiler flock. Table 3. Instrumentation used in broiler house measurements. Measured value Instrumentation Electricity consumption of on/off and adjustable fans CHAUVIN ARNOUX - P01105109Z Mini current clamps, Chauvin Arnoux group, France and HOBO Pendant event data logger, Onset, USA Electricity consumption of lights and tunnel ventilation fans CHAUVIN ARNOUX - P01105109Z Mini current clamps, Chauvin Arnoux group, France and Datataker DT80 data logger, Australia Total electricity consumption of the broiler house Current transformer CTSCM40-100/5, Howard Butler Ltd, England, 3 phase Entes EPR-04S digital powermeter, Entes, Turkey and HOBO Pendant event data logger, Onset, USA Energy consumption of heating ACTARIS CF ECHO II heat meter, Actaris, France and HOBO Pendant event data logger, Onset, USA Indoor temperature PT1000 sensors and A-Lab aCG-100 data logger Outdoor temperature Tinytag Ultra TGU-1500 data logger, Gemini data loggers, UK CO 2 emissions from combustion and electricity use were calculated for the broiler house. Emissions from combus- tion were calculated using the emission factors used in national GHG inventory (Table 4). Electricity emissions were calculated using the Motiva`s emission factors. Results were presented as kg of CO 2 per 1 000 kg of carcass weight. CO 2 emissions from heating were calculated using the most commonly used fuels (wood chips and sod peat) in poultry production in Finland. The emissions from liquefied petroleum gas (LPG) and oil were also calculated as a point of comparison. Two electricity sources were used in the calculations; mean electricity purchasing in Finland as a 5-year moving average (mean electricity) and electricity from renewable energy sources (green electricity). Green electricity was included because some of the broiler farms have their own electricity production with windmills. A G R I C U LT U R A L A N D F O O D S C I E N C E M. Rajaniemi & J. Ahokas (2015) vol 24: 10–23 17 The consumed fuel amount must be known for CO 2 emission calculations. This was estimated from the broiler house heating consumption by adding the heat losses of the heating canals (located between the broiler house and the boiler room) and furnace efficiency losses. It was assumed that the central heating system was used for peat, wood chips and oil and the direct heating system for LPG. Furnace efficiency for wood chips and sod peat was 80% and 87% for oil and LPG, respectively (Motiva 2010). Heat losses of the heating canal vary from 20 W m-1 to 30 W m-1 in Finland (MMM-RMO 2001). CO 2 emissions from the production of wood chips were not included. Table 4. Emission factors of heating fuels and electricity. Energy source Emission factor, g CO 2 kWh-1 Reference Wood chips 0 Tike 2014 Sod peat 367 Tike 2014 Heating fuel oil 263 Tike 2014 LPG 234 Tike 2014 Biomass from the field 0 Tike 2014 Green electricity (e.g. wind, hydropower) 0 Motiva 2014 Mean electricity (average of 5 years) 223 Motiva 2014 Results and discussion Total electricity consumption Total electricity consumption averaged 3800 kWh per flock and 0.08 kWh kg-1 of carcass weight. Electricity con- sumption was lower in our study than in previous in climatically warmer countries (Table 1) because of the low- er ventilation demand in Finland during the year. Figure 5 shows the daily electricity consumption of the broiler house during a one-year period. Figure 5 clearly shows two electricity consumption peaks during each rearing pe- riod. The first electricity consumption peak occurs at the beginning of the rearing period and the second peak at the end of the rearing period. Electricity consumption of lighting is the main reason for the first peak because the lights were kept on almost 24 hours a day at the beginning of the rearing period. Increased ventilation demand explains the second electricity consumption peak during the latter part of the rearing period. Hörndahl (2008) showed that electricity peaks occur at the beginning and latter part of the rearing period. In his study the high- est electricity consumption peak was at the beginning of the rearing period. This was most probably due to the lighting programme. 0 50 100 150 200 250 kW h da y- 1 Electricity consumption flock 1 flock 2 flock 3 flock 4 flock 5 flock 6 Month, year Fig. 5. Daily electricity consumption during the rearing of six broiler flocks. A G R I C U LT U R A L A N D F O O D S C I E N C E M. Rajaniemi & J. Ahokas (2015) 24: 10–23 18 Electricity consumption of the broiler house was highest during the warmest summer months. The main reason for this was the increased ventilation demand during the warmest days. Electricity is also consumed during the down time between flock rearing. The proportion of miscellaneous energy consumption increased in wintertime because four heat radiators with fans were used during this time. Electricity consumption of ventilation Figure 6 shows the weekly electricity consumption of ventilation fans during the rearing of six broiler flocks. The electricity consumption of on/off fans and adjustable fans averaged 1 200 kWh per flock and 0.025 kWh per kg of carcass weight. Their portion of the total electricity consumption during the rearing of a broiler flock averaged 37%. Ventilation electricity consumption was highest during the warmest summer months, when the maximum ventilation rate was needed to keep the inside temperature suitable for broilers. On/off and adjustable fans were used year-round for ventilation. Tunnel ventilation fans were mainly used during the warmest summer months. Ventilation demand increased along with broiler body mass and fan electricity consumption also increased dur- ing the latter part of the rearing period. Electricity consumption of lights The electricity consumption of lighting averaged 606 kWh per flock and 0.013 kWh per kg of carcass weight. It av- eraged 19% of the total electrical energy consumption during the rearing of a broiler flock. Energy consumption was highest during the first rearing week because lights were continuously on at the beginning (Fig. 7). After two rearing days the lights were dimmed stepwise and the broilers also experienced dark cycles. 0 100 200 300 400 500 600 700 22 25 28 31 34 37 40 43 46 49 52 3 6 9 12 15 18 21 kW h w ee k- 1 Week Energy consumption of on/off and adjustable fans 2013 2012 flock 1 flock 2 flock 3 flock 6 flock 4 flock 5 Fig. 6. Weekly electricity consumption of ventilation fans. 0 50 100 150 200 250 300 350 400 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 2 4 6 8 10 12 14 16 18 20 kW h w ee k- 1 Week Energy consumption of lighting 2012 2013 flock 1 flock 2 flock 3 flock 4 flock 5 flock 6 Fig. 7. Weekly lighting electricity consumption of six broiler flocks. A G R I C U LT U R A L A N D F O O D S C I E N C E M. Rajaniemi & J. Ahokas (2015) 24: 10–23 19 Heating energy consumption The measured heating energy consumption of the broiler house (12 flocks) averaged 61275 kWh flock-1 (range 16100–108500 kWh flock-1) and 1.3 kWh kg-1 of carcass weight (range 0.35–2.23 kWh kg-1 of carcass weight). This consumption includes pre-heating prior to the rearing period and heating during the rearing period. When canal losses and furnace efficiency are taken into account the total heating energy consumption is approximately 30% higher than the measured energy consumption. Figure 8 shows the heating energy consumption of 12 broiler flocks from June 2011 to May 2013. Heating energy consumption varied highly between different seasons and broiler flocks. Figure 9 shows the weekly heating energy consumption and ambient temperature during the rearing of six broiler flocks from 30th of January 2012 to 7th of January 2013. Heating energy consumption followed seasonal tempera- ture changes. The weekly heating energy consumption was mainly highest during cold days. -10 -5 0 5 10 15 20 25 0 20000 40000 60000 80000 100000 120000 kW h pe r d ow n- tim e an d re ar in g pe ri od Rearing period Heating during the rearing period Heating during the down- time Temperature M ea n ou td oo r em pe ra tu re °C Fig. 8. Heating energy consumption during the rearing of 12 broiler flocks. -25 -15 -5 5 15 25 0 2500 5000 7500 10000 12500 15000 17500 20000 22500 25000 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 Heating energy Outdoor temperature Te m pe ra tu re ° C kW h w ee k- 1 flock 1 Rearing week flock 2 flock 3 flock 4 flock 5 flock 6 Fig. 9. Weekly average heating energy consumption and ambient temperature during the rearing of six broiler flocks from 30th of January 2012 to 7th of January 2013. The last rearing week of each flock only includes 3–5 days, depending on the length of the rearing period. A G R I C U LT U R A L A N D F O O D S C I E N C E M. Rajaniemi & J. Ahokas (2015) 24: 10–23 20 Heating energy consumption was larger in our study than in several previous studies (e.g. Hörndahl 2008, Liang et al. 2009). One reason for this is that heating is needed year-round in Finland and outdoor temperatures dur- ing the wintertime are low compared to many other countries. However, broiler houses are highly heat insulated. The recommended U-values for walls and ceilings are 0.3 W m-2 K-1 and 0.22 W m-2 K-1, respectively (MMM-RMO 2001). Heat insulation had more impact on heat losses at the beginning of the rearing phases than during the lat- ter phase where more heat losses occurred through ventilation than through the structures. Heating energy constituted 94% of the total direct energy consumption and according to Figure 3 this is main- ly due to ventilation losses. Heat recovery from outlet ventilation air could be used to decrease heating energy input. There are still a few obstacles why heat recovery systems are not common in broiler housing in Boreal conditions. One reason is the challenging circumstances faced in broiler houses. Dust is a problem in all broil- er houses. Wintertime freezing is another evident problem. Both of these can obstruct the heat exchanger. For these reasons many farmers cut their heating costs by using less expensive heating fuel, e.g. wood chips. Due to high heating energy consumption the total direct energy consumption in our study was higher than in previ- ous studies from other countries. The theoretical heating energy consumption (Katajajuuri et al. 2006, Kivinen et al. 2013) is also lower in previous studies than the measured heating energy consumption in our study. This is probably because the theoretical calculations included several assumptions. They usually also ignored some air-flows (e.g. ventilation does not work identically, houses are not tight) and thermal bridges inside the house. Total direct energy consumption Figure 10 shows the energy consumption of heating and electricity of the broiler section during the six broiler rear- ing periods. The greatest total energy input amount of a broiler house is used for heating. Electricity consumption is only a minor part of the total direct energy consumption of a broiler house. The largest energy saving possibili- ties can hence be found in heating. CO 2 emissions Figure 11 shows that the CO 2 emissions caused by electricity and heating vary between 0–631 kg CO 2 1000-1 kg of carcass weight. The combustion of sod peat and wood chips cause the highest and lowest CO 2 emissions, respec- tively. Green electricity use does not significantly affect the emissions because it´s share of the total direct energy consumption is low. Figure 11 shows that the high use of fossil energy in heating on a farm can lead to high CO 2 emissions compared to a farm that only uses bioenergy for heating. Using energy effectively is the most impor- tant aspect even if bioenergy is used more for heating in the future. Because bioenergy is lower in cost than fossil energy it can lead to energy being used less effectively. -10 -5 0 5 10 15 20 0 20000 40000 60000 80000 100000 120000 En er gy c on su m pt io n du ri ng th e re ar in g pe ri od , k W h Rearing period Electricity during the down-time Miscellaneous Ventilation Lighting Heating during the rearing period Heating during the down-time Temperature M ea n ou td oo r em pe ra tu re °C Fig. 10. Mean outdoor temperature during the rearing period and heating energy and electricity consumption during the whole rearing period. A G R I C U LT U R A L A N D F O O D S C I E N C E M. Rajaniemi & J. Ahokas (2015) 24: 10–23 21 Figure 12 shows the CO 2 emissions of combustion and electricity (mean electricity) for broiler flocks during the different seasons. Wood chips and sod peat were used as heating fuel in the first and second figures, respectively. The second figure shows higher CO 2 emissions of production periods during the cold weather. If biofuels are used then the high CO 2 emissions can be avoided. 0 100 200 300 400 500 600 700 kg C O 2 pe r 10 00 k g of c ar ca ss w ei gh t Energy source Electricity Heating Fig. 11. CO 2 emissions of different fuel options. 0 100 200 300 400 500 600 700 800 900 1000 kg C O 2 em is si on s pe r 1 00 0 kg o f c ar ca ss w ei gh t Season Electric energy production Combusting (wood chips) 0 100 200 300 400 500 600 700 800 900 1000 kg C O 2 em is si on s pe r 1 00 0 kg o f c ar ca ss w ei gh t Season Electric energy production Combusting (sod peat) Fig. 12. The figure above shows the CO 2 emissions of wood chips combustion and electric energy use and the figure below the CO 2 emissions of the sod peat combustion and electric energy use of the broiler house. A G R I C U LT U R A L A N D F O O D S C I E N C E M. Rajaniemi & J. Ahokas (2015) 24: 10–23 22 Beef and dairy production causes the greatest GHG emissions in the animal production industry in the EU. Poul- try emissions per produced meat kilogramme are lower than those of beef (e.g. Weidema et al. 2008, Lesschen et al. 2011, Weis and Leip 2012). This is because beef and dairy production cause more CH 4 and N 2 O emissions than poultry production. Poultry is also more effective at converting feed energy to meat energy and less field area is needed for feed production. The greatest GHG emissions of broiler meat production come from land use and land use change (Fig. 4). Feed production therefore causes the largest GHG emissions when all production inputs are considered. CO 2 emissions from heating depend on the fuel source in questions. Emissions from electricity are only a small part of the total emission load of broiler production. Conclusion Results showed that heating energy was the highest direct energy input in the broiler house and that is where the largest direct energy saving potential of broiler houses can be found. Most of the energy is lost through ven- tilation. A heat recovery system, optimally working ventilation system and good insulation save heating energy. Finnish farmers are currently not interested in using heat recovery systems on broiler farms because no experi- ence exists on the functionality of heat exchangers in cold climates. Heating also causes high CO 2 emissions when it is based on fossil fuels. Many Finnish broiler farms currently use bioenergy for heating. This means that the CO 2 emissions of combusting are low compared to countries with lower heating energy consumption that is pro- duced by fossil energy. Electricity was only a small portion of the total direct energy consumption of the broiler house. Ventilation and lighting consumed 37% and 19% of the total electricity consumption, respectively. Energy-efficient lights and fans hence have an important role in conserving electricity. Modern broiler house management is well organised. The houses have automated illumination, ventilation and feeding systems. These function effectively and no high en- ergy saving potential can be found. Feed production energy consumption has to be addressed when total energy consumption is inspected. When only direct energy consumption is looked at, ventilation control and heat recovery from ventilation are important. Energy efficiency should be taken into account, especially when new houses are built and when renovations are necessary in older broiler houses. Acknowledgements Our study was performed in the Energy Academy project financed by the Rural Development Programme for Main- land Finland 2007‒2013. We would also like to thank the following people: Marko Kajoskivi (University of Helsin- ki) for helping with data collection and measuring, the farmer participating in our project and Tapani Jokiniemi (University of Helsinki) and Hannu Mikkola (University of Helsinki) for comments on earlier versions of this paper. References agrEE 2012. State of the art on energy efficiency in agriculture. Country data on energy consumption in different agro-production sectors in the European countries. Agriculture and Energy Efficiency (agrEE). Cited 10 December 2013. http://www.agree.aua.gr/ Files/Agree_State.pdf Ahokas, J., Rajaniemi , M., Mikkola , H., Frorip , J., Kokin , E., Praks , J., Poikalainen, V., Veermäe, I. & Schäfer, W. 2014. Energy use and sustainability of intensive livestock production. In: Bundschuh, J. & and Chen, G. (ed.). Sustainable Energy Solutions in Agri- culture. London, UK: CRC Press. 195–244. Barber, E.M., Classen, H.L. & Thacker, P.A. 1989. Energy use in the production and housing of poultry and swine - an overview. Canadian Journal of Animal Science 69: 7–21. Baughman, G. R., & Parkhurst, C. R. 1977. Energy Consumption in Broiler Production. Transactions of the ASAE 20: 341–344. Bokkers, E.A., van Zanten, H.H. & van den Brand, H. 2010. Field study of a heat exchanger on broiler performance, energy use, and calculated carbon dioxide emission at commercial broiler farms, and the experiences of farmers using a heat exchanger. Poul- try Science 89: 2743–2750. CIGR 2002. 4th Report of Working Group on Climatization of Animal Houses. Heat and moisture production at animal and house level. International Commission of Agricultural Engineering, Section II. Editors S. Pedersen and K. Sällvik. Cited 5 December 2014. Available on the internet: http://www.cigr.org/documents/CIGR_4TH_WORK_GR.pdf EC 2009. Directive 2009/28/EC of the European Parliament and of the Council of 23 April 2009 on the promotion of the use of en- ergy from renewable sources and amending and subsequently repealing Directives 2001/77/EC and 2003/30/EC. Cited 30 Sep- tember 2014. http://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32009L0028&from=FI EU 2012. Directive 2012/27/EU of the European Parliament and of the Council of 25 October 2012 on energy efficiency, amending Directives 2009/125/EC and 2010/30/EU and repealing Directives 2004/8/EC and 2006/32/EC. Cited 30 September 2014. http:// eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2012:315:0001:0056:en:PDF A G R I C U LT U R A L A N D F O O D S C I E N C E M. Rajaniemi & J. Ahokas (2015) 24: 10–23 23 Government regulation 2009. Valtioneuvoston asetus (1000/2009) maatilan energiasuunnitelmatuesta. Cited 20 April 2013. http://www.finlex.fi/fi/laki/alkup/2009/20091000 (in Finnish) Government regulation 2011. Valtioneuvoston asetus (375/2011) broilereiden suojelusta. Cited 20 April 2013. http://www.fin- lex.fi/fi/laki/alkup/2011/20110375 (in Finnish) Harrinkari, T. & Raukola, I. 2009. Siipikarjantuotanto elinkeinona. Helsinki: Opetushallitus. 240 p. (in Finnish) Hörndahl, T. 2008. Energy Use in Farm Buildings – a study of 16 farms with different enterprises. Revised and translated sec- ond edition. Swedish University of Agricultural Sciences, Faculty of Landscape Planning, Horticulture and Agricultural Science. Report 8. 43 p. Cited 15 May 2014. http://pub.epsilon.slu.se/3396/1/Eng-rapport145-v1.pdf Katajajuuri, J.M., Grönroos, J., Usva, K., Virtanen, Y., Sipilä, I., Venäläinen, E., Kurppa, S.,Tanskanen, R., Mattila, T. & Virtanen, H. 2006. Broilerin fileesuikaleiden tuotannon ympäristövaikutukset ja kehittämismahdollisuudet. Maa- ja elintarviketalous 90. MTT, Jokioinen. 118 p. Cited 15 August 2014. http://www.mtt.fi/met/pdf/met90.pdf (in Finnish) Kivinen, T., Heikkinen, J., Heimonen, I. & Laamanen, J. 2013. Broilerihallin ilmanvaihdon hienosäätö. MTT raportti 112. MTT: Jokioinen. 74 p. Cited 15 August 2014. http://jukuri.mtt.fi/handle/10024/481343 Lesschen, J.P., van den Berg, M., Westhoek, H.J., Witzk, H.P. & Oenema, O. 2011. Greenhouse gas emission profiles of Europe- an livestock sectors. Animal feed science and technology 166–167: 16–28. Liang, Y., Tabler, G.T., Watkins, S.E., Xin, H. & Berry, I.L. 2009. Energy use analysis of open-curtain vs. totally enclosed broiler houses in Northwest Arkansas. Applied Engineering in Agriculture 25: 577–584. Mannfors, B., & Hautala, M. 2011. Eläinten hyvinvointiin perustuva tuotantoeläinrakennusten mikroilmasto: Ilmanvaihtoon ja lämpötilaan liittyvät suositukset. Maataloustieteiden laitoksen julkaisuja 6. Helsingin yliopisto. 102 p. (in Finnish) MMM-RMO 2001. Maa- ja metsätalousministeriön rakentamismääräys- ja ohjeet. Liite 10 MMM:n asetukseen tuettavaa raken- tamista koskevista rakentamismääräyksistä ja suosituksista (100/01): Maatalouden tuotantorakennusten lämpöhuolto ja huo- neilmasto MMM-RMO C2.2. Cited 20 April 2013. http://www.finlex.fi/data/normit/8673-01100fil10.pdf (in Finnish) Motiva 2010. Polttoaineiden lämpöarvot, hyötysuhteet ja hiilidioksidin ominaispäästökertoimet sekä energian hinnat. 5 p. Cited 20 April 2013. http://www.motiva.fi/files/3193/Polttoaineiden_lampoarvot_hyotysuhteet_ja_hiilidioksidin_ominaispaastoker- toimet_seka_energianhinnat_19042010.pdf (in Finnish) Motiva 2014. CO2 päästökertoimet. Cited 20 April 2013. http://www.motiva.fi/taustatietoa/energiankaytto_suomessa/co2-lasken- taohje_energiankulutuksen_hiilidioksidipaastojen_laskentaan/co2-paastokertoimet (in Finnish) Mäkinen, T., Soimakallio, S., Paappanen, T., Pahkala, K. & Mikkola, H. 2006. Liikenteen biopolttoaineiden ja peltoenergian kas- vihuonekaasutaseet ja uudet liiketoimintakonseptit. VTT Tiedotteita 2357. Helsinki: Edita Prima Oy. 134 p. (in Finnish) Pimentel, D. 1980. Handbook of energy utilization in agriculture. Boca Raton, Florida: CRC Press. 496 p. Siipikarjaliitto 2010. Broilerintuotannon vaiheet. Cited 15 August 2013. http://www.siipi.net/index.php/broileriyhdistys/tu- otantorakenne (in Finnish) Sonesson, U., Cedenberg, C. & Berglund, M. 2009. Greenhouse gas emissions in chicken production. Decision support for cli- mate certification. Report 6. 19 p. TEM 2008. Pitkän aikavälin ilmasto- ja energiastrategia. Valtioneuvoston selonteko eduskunnalle 6. päivänä marraskuuta 2008. Cited 20 April 2013. http://www.tem.fi/files/20585/Selontekoehdotus_311008.pdf (in Finnish) TEM 2013. Kansallinen energia- ja ilmastostrategia. Valtioneuvoston selonteko eduskunnalle 20. päivänä maaliskuuta 2013. Työ ja elinkeinoministeriön julkaisuja, Energia ja ilmasto 8. 53 p. Cited 24 September 2014. https://www.tem.fi/files/36266/Ener- gia_ja_ilmastostrategia_nettijulkaisu_SUOMENKIELINEN.pdf Tike 2012. Energiankulutuksen jakautuminen energialähteittäin. Cited 11 May 2014. http://www.maataloustilastot.fi/maata- louden-rakennetutkimus Tike 2013a. Lihantuotanto Suomessa. Cited 11 May 2013. http://www.maataloustilastot.fi/tilasto/2026 Tike 2013b. Maatalouden energiankulutus vajaa kolme prosenttia. Tietosarka 2. Cited 18 September 2014. http://tike.multiedi- tion.fi/tike/tietosarka/2013/huhtikuu/paakirjoitus.php (in Finnish) Tike 2014. Fuel classification 2014. Cited 2 April 2014. http://www.stat.fi/polttoaineluokitus. Weidema, B.P., Wesnæs, M., Hermansen, J., Kristensen, T. & Halberg, N. 2008. Environmental improvement potentials of meat and dairy products. JRC Scientific and technical reports, Spain. 194 p. Cited 1 September 2014. http://ftp.jrc.es/EURdoc/JRC46650.pdf Weiss, F. & Leip, A. 2010. Quantification of GHG emissions of EU livestock production in form of a life cycle assessment (LCA). In: European Commission, Joint Research Centre. Evaluation of the livestock sector`s contribution to the EU greenhouse gas emis- sions (GGELS). Final report. p. 162–189. Cited 13 June 2014. http://ec.europa.eu/agriculture/analysis/external/livestock-gas/ full_text_en.pdf Weiss, F. & Leip, A. 2012. Greenhouse gas emissions from the EU livestock sector: A life cycle assessment carried out with the CAPRI model. Agriculture, Ecosystems and Environment 149: 124–134. Direct energy consumption and CO2 emissions ina Finnish broiler house – a case study Introduction Material and methods Results and discussion Total electricity consumption Electricity consumption of ventilation Electricity consumption of lights Heating energy consumption Total direct energy consumption CO2 emissions Conclusion Acknowledgements References