Internal Heat Gains

Internal heat gain (IHG) is divided into IHG People, IHG Equipment, and IHG Lighting. The input for IHG is required for cooling load calculations and building simulations.

IHG People

Persons

The heat load for people is the maximum heat output, expressed in W/m², W, or as the total number of people. For people, the heat load is calculated based on specified Clo and MET values. If W/m² is entered, calculations are based on fixed wall dimensions, excluding wall thickness. The total heat load includes both sensible and latent heat.

 

Summer clothing

This is the thermal insulation of the body due to worn clothing, also known as clothing insulation. 1 clo = 0.155 m²·K/W (ISSO 19 2.1.1.). Because this setting is used for cooling load, we specify people wearing light clothing to ensure higher heat production. The summer period runs from April 27 to September 27.

Winter clothing

This is the thermal insulation of the body due to worn clothing, also known as clothing insulation. 1 clo = 0.155 m²·K/W (ISSO 19 2.1.1.). Because this setting is used for building simulation in the winter, we specify people wearing heavy clothing to ensure lower heat production and thus requiring more heating. If a chair is used, the insulation due to the chair should be added (0.15 clo for example, for an office chair). The winter period runs from September 28 to April 26.

Clothing ensemble	[clo]
Naked	0
Shorts	0,1
Tropical cloths: (Slip, shorts, open-neck shirt with short sleeves or T-shirt, thin socks, and sandals)	0,3
Light summerwear: (Slip, light trousers, open-neck shirt with short sleeves, thin socks, and shoes)	0,5
Light workclothes: (Underwear, cotton work shirt with long sleeves, long work trousers, wool socks, and shoes or slip, petticoat, stockings, dress, and shoes)	0,7
Indoor winter clothes: (Underwear, long-sleeved shirt, trousers, long-sleeved sweater, thick socks, and shoes; or slip, stockings, blouse, long skirt, coat, and shoes)	1,0
Outdoor winter clothes: (Cotton underwear with long sleeves and pants, shirt, suit with long pants, jacket and vest, wool socks, and sturdy shoes)	1,5

 

Activity MET-Values

These are predefined activities that include a wattage per person and a metabolism rate (M).

1 MET = 58.2 W/m². For an adult, a space of 1.8 m² per person should be calculated.

Activity	Met-value	Total Power (Watt)	Tangible assets at 22 ° C and clo = 0.8 (W)
Resting	0,81	85	74
RGD-standard	1,20	126	80
Sedentary office work	1,24	130	83
Typing	1,52	160	89
Low active sedentary work	2,00	210	101
Low active standing work	2,86	300	131
Active sports	3,81	400
Heavy sports	4,76	500

 

The above table has been taken from the cooling load norm NEN 5067 (page 27, table 1 and 1a) and it is similar to ISSO 32 (Table 6) and ISSO 8 (Table 14).

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IHG Equipment

Thermal power

The thermal power is the maximum amount of power of heat which is generated by the equipment, expressed in W or W/m². When expressing the power in W/m², the gross surface area of the floor is taken into consideration. In this this case the calculations are based on fixed wall dimensions, i.e. centre point dimensions excluding wall thicknesses. See; Dimensions.

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Sensible part

Sensible heat is the energy per unit of time and unit of area that is released as heating of air into the atmosphere. This applies when entering power in W or W/m².

Of which convective part

This is the convective part of sensible heat. The remaining part is radiant heat.

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IHG lighting

Thermal power

The thermal power is the maximum amount of power of heat which is generated by lighting, expressed in W or W/m². When expressing the power in W/m², the gross surface area of the floor is taken into consideration. In this case the calculations are based on fixed wall dimensions, i.e. centre point dimensions excluding wall thicknesses. See Dimensions.

 

In the EPG calculations the thermal power of lighting is only taken into account if the project settings specify that lighting power needs to be considered in detail. In order to determine the lighting power in case of a flat rate method, the power is related to the functions of use inside the building.

• Houses: no lights during daytime, 15 W / m² in living room and kitchen in the evening;
• Schools: 10 W / m²;
• Offices: see ISSO Publicatie 32 Afgegeven vermogen door verlichting

Lightning has presence detection

This option allows you to choose whether the lighting is controlled based on the presence and absence of people. An infrared sensor is used to detect any movement inside the room and to switch on the lights upon detected movement.

Illuminated ceiling

This option allows you to choose whether the ceiling is illuminated. If so, the ceiling may accumulate radiant heat.

Lighting has air exhaust

This option allows you to apply exhaust to the luminaires using the ventilation system of the corresponding room. If this box has been checked, the heat gain may be reduced depending on the way of applying exhaust (position and type). Exhaust should be applied to at least 70% of the luminaires in the building (calculation zone) in an EPG calculation in order to appraise this in the EPC.

Building simulation: With air extraction via luminaire and ceilingd         CF_l =0,68

Position

This option only applies if the lighting has no air exhaust. Based on this position, a convection factor (CFL) is determined.

Type

This choice concerns the type of extract which is applied in case the lighting does have an air exhaust. A reduction factor is determined based on this choice and the flow rate.

• Through plenum; extract is applied via the airless space in the lowered ceiling. This is the least efficient type of suction.
• Through insulated duct; extract is applied via an insulated duct, to lead away as much heat as possible. This is the most efficient type of suction.
• Through uninsulated duct; suction is applied via an uninsulated duct. A slight amount of heat will leak away through the duct into the room.

Flow rate

The flow rate indicates the amount of air being sucked away per 100 W of installed power. This quantity may be a design requirement to be taken into account.

• Flow rate of 20 m³ / h per 100W or 0.0056 m³ / s
• Flow rate of 30 m³ / h per 100W or 0.0083 m³ / s
• Flow rate of 50 m³ / h per 100W or 0.0140 m³ / s
• Flow rate of 100 m³ / h per 100W or 0.0280 m³ / s

The contribution of the lighting to the cooling load is computed from the specified input according to a set of calculation rules, which can be found in the following standards:

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Control

The control affects the way the software deals with switching the lighting on and off.  This parameter does not affect the cooling load calculations.

• Manual: no control is applied to the lighting.
• Central control: the lighting system is switched on and off in the complete building
• Sweep pulse: the corresponding lighting is switched off at predefined times using a sweep pulse.
• Daylight control: the lighting in the building is controlled based on a light sensor measuring the amount of incoming light. The light sensor may be installed for each room or for each luminaire.
• Sweep pulse and daylight: The lighting is switched off at specified times (e.g. during lunchtime) using a sweep pulse and simultaneously a light sensor is applied to measure the amount of incoming light on the surface.
• Room control: the lighting is controlled for each room separately.
• Room and facade control: this is equivalent to room control with an added option to control the facade separately.

Daylight control

 

This option allows you to choose whether the daylight control should only switch the lights on when it gets too dark outside and the lights have to be switched off manually, or whether the daylight control should both switch the lights on when it gets too dark outside and switch them off when it gets light outside. This entry only applies in case daylight control was chosen.

• Only on; only control switching the lights on (which then keep burning the whole day)
• On and off; control switching the lights both on and off

Intensity “on”

This is the maximum intensity of the light outside at which the lighting inside should be switched on. This entry only applies to daylight control

Intensity “off“

This is the minimum intensity of the light outside at which the lights inside should be switched off. This entry only applies to daylight control which both controls switching the lights on and off.

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