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The indoor climate of the home

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This white paper is one of a series of thematic white papers covering various aspects of electrical installations in houses, flats and residential units. They are aimed at architects, designers, specification writers, decision makers and students.

To a large extent, the interior climate of a home determines how good the occupants feel in it. A correct interior temperature that does not fluctuate too much and sufficient fresh air create a pleasant living environment for the occupants. However, heating and cooling are the home’s great energy consumers.

So in this white paper we look at the different types of heat pump, zone heating - whether or not controlled by an Integrated Home System (IHS) - and we also investigate the use of decentralised circulating pumps. We conclude the heating section by describing how existing radiators can be boosted by means of a fan.

We also consider what needs to be taken into account when installing air conditioning, and we discuss the various methods of ventilating the home. Finally, we describe briefly how we can keep driveways, footpaths and parking spaces free of snow and ice.

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The indoor climate of the home

  1. 1. WHITE PAPER THE INDOOR CLIMATE OF THE HOME Guy Kasier April 2017 ECI Publication No Cu0257 Available from www.leonardo-energy.org
  2. 2. Publication No Cu0257 Issue Date: April 2017 Page i Document Issue Control Sheet Document Title: The indoor climate of the home Publication No: Cu0257 Issue: 01 Release: Public Content provider(s) Guy Kasier Author(s): Guy Kasier Editorial and language review Carol Godfrey Content review: Bruno Dewachter Document History Issue Date Purpose 1 April 2017 Initial public release 2 3 Disclaimer While this publication has been prepared with care, European Copper Institute and other contributors provide no warranty with regards to the content and shall not be liable for any direct, incidental or consequential damages that may result from the use of the information or the data contained. Copyright© European Copper Institute. Reproduction is authorized providing the material is unabridged and the source is acknowledged.
  3. 3. Publication No Cu0257 Issue Date: April 2017 Page ii CONTENTS 1. Introduction................................................................................................................................................ 1 2. Types of heat pump .................................................................................................................................... 2 2.1. Exterior air as source .......................................................................................................................................2 2.2. The ground as a heat source............................................................................................................................3 2.3. Water as source...............................................................................................................................................3 3. Zone heating and IHS control...................................................................................................................... 4 3.1. The traditional heating installation .................................................................................................................4 3.2. Zone heating....................................................................................................................................................4 3.3. Other advantages of zone heating and IHS control.........................................................................................5 4. Decentralised circulating pumps................................................................................................................. 6 5. Boosting a radiator ..................................................................................................................................... 7 5.1. Convection.......................................................................................................................................................7 5.2. A fan in the radiator.........................................................................................................................................7 6. Air conditioning .......................................................................................................................................... 8 6.1. Energy saving measures ..................................................................................................................................8 6.2. Calling on air conditioning when necessary ....................................................................................................8 7. Ventilating the home .................................................................................................................................. 9 7.1. System A ..........................................................................................................................................................9 7.2. System B ..........................................................................................................................................................9 7.3. System C ..........................................................................................................................................................9 7.4. System D..........................................................................................................................................................9 7.5. Existing homes...............................................................................................................................................10 8. Keeping driveways and footpaths free of ice ............................................................................................ 11 8.1. Working method............................................................................................................................................11
  4. 4. Publication No Cu0257 Issue Date: April 2017 Page 1 1. INTRODUCTION This white paper is one of a series of thematic white papers covering various aspects of electrical installations in houses, flats and residential units. They are aimed at architects, designers, specification writers, decision makers and students. To a large extent, the interior climate of a home determines how good the occupants feel in it. A correct interior temperature that does not fluctuate too much and sufficient fresh air create a pleasant living environment for the occupants. However, heating and cooling are the home’s great energy consumers. So in this white paper we look at the different types of heat pump, zone heating - whether or not controlled by an Integrated Home System (IHS) - and we also investigate the use of decentralised circulating pumps. We conclude the heating section by describing how existing radiators can be boosted by means of a fan. We also consider what needs to be taken into account when installing air conditioning, and we discuss the various methods of ventilating the home. Finally, we describe briefly how we can keep driveways, footpaths and parking spaces free of snow and ice.
  5. 5. Publication No Cu0257 Issue Date: April 2017 Page 2 2. TYPES OF HEAT PUMP In a well-insulated home, it is possible to use an energy-efficient heat pump for heating as well as for producing sanitary hot water. In some cases, cooling in the summer can even be carried out with the same appliance. There are a number of options available that are worth considering, the most important of which involve the type of source and whether to go with an air heating or water heating system. In principle, the operation of a heat pump can be compared to that of a refrigerator or deep freeze. The refrigerator extracts heat from the interior and releases it to the exterior. On the back of a refrigerator there is a grille with fine tubes, along which heat is released to the surrounding air. A heat pump extracts heat from the air, water or ground and transports that heat to a heat exchanger which brings the central heating installation’s air or water up to temperature. There are different types of heat pump, based on the source and on the system used to distribute the heat: 2.1. EXTERIOR AIR AS SOURCE - Air/air heat pump: Heat is extracted from the outside air and converted to warmer air by a heat exchanger. This heated air is then distributed throughout the home by means of a forced air system (a fan, a network of pipes and grilles). -Air/water heat pump: Outside air is used as a source here as well, but the extracted heat is transferred to a water circuit that can be used for underfloor heating, radiators and sanitary hot water. The cost to install air source heat pumps is lower than for other systems, but they do have one disadvantage: if the outside air gets too cold, the system becomes less efficient. Air systems are predominantly used in temperate climate zones and are not recommended for regions with long, cold winters. Figure 1: Schematic illustration of an air/water heat pump. (Photo source: Fotolia)
  6. 6. Publication No Cu0257 Issue Date: April 2017 Page 3 2.2. THE GROUND AS A HEAT SOURCE In this case, heat is extracted from the ground and converted into hot water. This is called a ground/water heat pump. The temperature of the ground remains much more constant throughout the entire year, so this system is quite efficient, even during cold winters. There are two types of system: a horizontal and a vertical ground heat exchanger: - Horizontal ground heat exchanger: Flexible PE piping is installed at a specified depth (e.g. 1.5 m) beneath the ground level in the garden. This closed loop then transfers its heat to the heat pump. The surface area required for this is much larger than that of the space to be heated, so this system is not suitable for a smaller garden in the city. - Vertical ground heat exchanger: One or more vertical holes are drilled into the ground. In each opening, two PE pipes are installed (one descending and one ascending), which together form a closed loop. The liquid mixture in the PE pipes draws the heat from the ground and transfers it to the heat pump. Such a system can be deployed in ground having a limited surface area, but boreholes obviously still need to be made. Since the colder return water can lower the temperature of the ground, the efficiency of this system may start to decline toward the end of the heating season. If the temperature of the ground drops too much, the ground is said to be depleted. A proper balance must be struck between the extraction of heat from the ground in winter and the natural rewarming of the ground in summer. The latter can also be achieved by reversing the function of the heat pump in summer: the home is cooled and the excess heat transferred to the ground. 2.3. WATER AS SOURCE A watercourse or, better still, groundwater can also be tapped as a heat source. Two wells are drilled into the ground at a reasonable distance from each other. In contrast to a vertical ground/water system, this is an open system. Groundwater is pumped from the first well to the heat pump. The heat is transferred to a heat exchanger, and colder return water is then pumped to the second well. If desired, this system can be reversed in summer, with the colder groundwater from the second well being used to cool the home. Excess heat is then stored in the first well.
  7. 7. Publication No Cu0257 Issue Date: April 2017 Page 4 3. ZONE HEATING AND IHS CONTROL In this section we consider the advantages of zone heating and how it is controlled within an Integrated Home System (IHS). 3.1. THE TRADITIONAL HEATING INSTALLATION In a traditional heating installation, just one room thermostat is provided, usually located in the living room. The radiators in the other rooms are fitted with a thermostatic valve so, in principle, the occupant can set the level of heating in each room. However, this is not always successful, as we will explain now in more detail. Once the temperature in the living room has reached the temperature set on the thermostat, the heating boiler will switch to a lower temperature for the heating water. For example, that may be 30°C. If another room then needs heating, the boiler water temperature is too low to do it. Once the room temperature in the living room rises just above the value set on the thermostat, the heating boiler will stop operating, and this applies to the other rooms as well. For example, this may happen when the room temperature in the living room has risen through the use of a fireplace, a wood burning stove or by incoming heat from the sun. In a living room with an open-plan kitchen, cooking activities (use of the oven or hob, for example) can also increase the room temperature, with the result that the other rooms in the home will not be heated. A solution could be to install multiple thermostats but there are very few heating boilers that can be connected to two thermostats. Even then this does not entirely solve the problem. If the additional thermostat is installed in bedroom one, but there is only activity in the other bedrooms or in the office, then bedroom one will also have to be heated in order to heat up the other bedrooms. 3.2. ZONE HEATING Each room is provided with separate zone heating. Each zone is connected via a solenoid valve with the heating boiler and the solenoid valves are then controlled by the outputs from the IHS system. Each zone is further equipped with an electronic temperature sensor and these are also connected to the IHS system. To control a zone, a few push-buttons, sometimes in a button panel (with or without a display), are installed in the zone. Finally, one output from the IHS system is connected with the so-called boiler contact. Once the latter is closed, the boiler will start operating. Using a software setting, the installer will ensure that if one or more valves are opened (there is heating demand), the boiler contact is closed. If all valves are closed, the boiler contact is open and the heating boiler knows that there is no more heating demand. The user can set the heating to day or night mode using the push-buttons in the room. With two other buttons, the room temperature can be increased or decreased by half a degree at a time, each time they are pressed. Moreover, nowadays it is also possible to carry out these operations via an app on a smartphone or tablet, or via a small touchscreen from the switch manufacturer.
  8. 8. Publication No Cu0257 Issue Date: April 2017 Page 5 Figure 2: Touchscreens like this one can control not only the lighting and the roller shutters, but also the room temperature. (Photo source: Jung) 3.3. OTHER ADVANTAGES OF ZONE HEATING AND IHS CONTROL Besides the individual controls for each room, group controls can also be carried out from a touchscreen in the living room, or via a smartphone. The latter can even be used to control the heating from outside the home. This can be convenient for people working irregular hours but who nevertheless want to heat up the living room before they get home. With the “All Off” buttons by the front door and garage door, or with the “goodnight” button next to the bed, all heating for the entire home can be immediately put into night mode, without the occupant having to go to each room. The same applies to activating the day mode on arrival home. From the living room or another room, it is also possible to temporarily increase the basic heating for the bathroom to a pleasant enough temperature to take a shower or bath. The conscious use of an IHS-controlled heating system reduces the energy costs for the user because only the rooms that are in use are heated.
  9. 9. Publication No Cu0257 Issue Date: April 2017 Page 6 4. DECENTRALISED CIRCULATING PUMPS If there is no IHS system, there is another way of saving energy: the use of small decentralised circulating pumps. Of course, without an IHS the user does not have any integrated control options for lighting, shutters, sunscreens etc. The German company Wilo has developed a heating system that does not make use of a central circulating pump, but of small decentralised circulating pumps. These are small enough to fit in the palm of the hand. Each radiator or floor heating circuit is equipped with its own pump. In order to participate in zone heating, each room is also fitted with a control interface. One side is connected with the pumps in the rooms and the other with a BUS system. The Fraunhofer Institute carried out a comparative study of two equivalent, adjacent, detached houses. They were not lived in, so there could be no differences due to human influences. One house was equipped with a classic central circulating pump, the other with the decentralised pumps. The measurement period was from October to the end of April. Converted into primary energy (gas and electricity), the house with the decentralised pumps registered a 21% saving. Figure 3: The energy saving circulating pumps really are very small. (Photo source: Wilo) Figure 4: Each room has its own control interface. (Photo source: Wilo)
  10. 10. Publication No Cu0257 Issue Date: April 2017 Page 7 5. BOOSTING A RADIATOR 5.1. CONVECTION A traditional radiator works according to the convection principle. Hot water is sent through the radiator, heating cold air surrounding the bottom of the radiator. The heated air rises through the radiator into the room, circulating the warm air throughout the room and moving the remaining cold air to the bottom of the radiator to be heated. This natural process is relatively slow, especially for heating systems employing low water temperatures. 5.2. A FAN IN THE RADIATOR To speed up a room’s heating process, fans can be fitted into certain radiators. Using a control panel on the radiator, the user can choose between conventional heating or boost. Of course there does need to be a socket near the radiator to provide the system with power. The efficiency of the radiators can be increased by 30% through better temperature control and a shorter heating time, resulting in a lower energy bill. Figure 5: This radiator has been fitted with two fan modules. (Photo source: Jaga) In addition to the built-in system, there are also stand-alone models that can be installed on top of an existing radiator.
  11. 11. Publication No Cu0257 Issue Date: April 2017 Page 8 6. AIR CONDITIONING Sometimes it can get too hot in the home. That is certainly the case in certain parts of Europe where the temperatures can be high, even in the spring and autumn. This makes comfortable sleeping impossible, unless good air conditioning is fitted. 6.1. ENERGY SAVING MEASURES Air conditioning consumes energy, and we want to avoid that as much as possible. Therefore, it is important to design the home to keep to a minimum the amount of exterior heat that can get in. In the summer, an overhang can prevent the sun that is high in the sky from radiating its heat through glazed areas. During the winter, the sun is low in the sky and can still give some heat to the home. The occupants can also adapt their behaviour by keeping doors and windows shut as much as possible during the day. Windows can only be opened in the evening, when the exterior air becomes cooler than the interior air. Moreover, a proper sunscreen can provide a solution for keeping the hot solar radiation outside. It is preferable to choose an automatic system so that, if the occupants are not at home, the sunscreen will still do its job. The occupants will not come home to find their home too hot. 6.2. CALLING ON AIR CONDITIONING WHEN NECESSARY During longer periods of high temperatures, the above measures alone will not be sufficient to keep the temperature inside the home at an acceptable, comfortable level. At these times, we need to call upon air conditioning. The operation is somewhat similar to that of a refrigerator or freezer. It always contains a condenser and compressor. Air conditioners can be monobloc, consisting of one piece, or a split system, in which the condenser group is installed outside and a cooling pipe is connected to the appliance inside the home. Homes are mostly equipped with split systems, as they create less noise inside the house. Usually a thermostat is installed on the wall, and in certain cases the appliance can be operated with a remote control or even an IHS system. Split systems can be mono split, in which each interior unit has its own exterior unit, or multi split, in which all internal units are connected to a larger exterior unit. In order to cool multiple rooms, a multi split system is more attractive. Figure 6: A typical split system whereby the bottom part is installed in the exterior air. (Photo source: Ecoair)
  12. 12. Publication No Cu0257 Issue Date: April 2017 Page 9 7. VENTILATING THE HOME Ventilating a home is an important factor in creating a pleasant and healthy living environment for the occupants but it also has benefits for the home itself. For example, excessive humidity in the air can result in mould formation. Nowadays newly-built houses are very well insulated and air-tight and it is therefore essential to install a ventilation system. There are four systems available on the market: 7.1. SYSTEM A Grilles through which fresh exterior air is supplied are fitted above the windows in the home’s dry rooms. In the damp rooms, a vertical vent with adjustable grilles extracts the polluted air naturally. Grilles in interior walls or doors make sure that an air flow is created from the dry rooms to the damp rooms. The degree of ventilation depends greatly on the difference in temperature and pressure between the interior and exterior climate. This is a very simple system, but it is not very efficient as little or no adjustment is possible. 7.2. SYSTEM B Here, fans in the dry rooms ensure the supply of fresh air. The flow of air to the damp rooms and the extraction of polluted air are done in the same way as with system A. With system B, the degree of ventilation is less dependent on the exterior climate. Of course, some energy is consumed by the fans. Another disadvantage can be the background noise of the fans in the different rooms. 7.3. SYSTEM C This works the other way round. Fresh air enters the dry rooms via vents in the windows. The polluted air is extracted from the damp room by means of a fan. This system guarantees good air quality in the home, and does so under different weather conditions. There is also a System C+, where the extraction is provided by an intelligent control so that the air flow can be controlled. A motion detector in the damp room detects a person’s presence and temporarily increases the air extraction. A CO detector can also be used as a trigger for obtaining accelerated air extraction when the CO value becomes too high. 7.4. SYSTEM D System D really combines systems B and C. There is both a mechanical supply and extraction by means of fans. The system’s controls ensure the supply and extraction are always tuned to each other, avoiding underpressure or overpressure. System D can be complemented with a heat recovery system. The cold exterior air is routed to a heat exchanger where it is preheated with heat from the polluted extracted air (that is already at room temperature). Of course, the fresh air and the polluted air are not mixed together. This method delivers an energy saving. In the summer, it works the other way round. The hot air is partly cooled down in the heat exchanger due to the lower interior air temperature. This reduces the need for additional cooling with air conditioning.
  13. 13. Publication No Cu0257 Issue Date: April 2017 Page 10 Figure 7: Example of system D with a heat recovery system. (Illustration source: www.interieurdesigner.be) 7.5. EXISTING HOMES In existing homes that are not yet fitted with a ventilation system, we can do two things. First, there is the kitchen where air humidity and food odours are produced. The familiar extractor hood above the cooker takes care of the extraction of polluted air while cooking. Usually, older homes are not very air-tight, with the result that fresh exterior air is supplied through cracks, the letterbox, under doors etc. In the bathroom and toilet, we can rely on a bathroom fan installed in an exterior wall or in the ceiling. In the latter case, the polluted air is extracted through a pipe to a roof tile with an air vent. After all, it is not the intention that the polluted and humid air comes into contact with the roof structure. Figure 8: Example of a bathroom fan. (Photo source: Maico) In its simplest form, the bathroom fan will be connected to the bathroom light switch. When the light is switched on, the fan runs. However, there is also a version which includes a timer in the fan. The fan still comes on when the light is switched on, but after the light has been switched off, the fan continues to run for a few more minutes in order to remove unpleasant odours or humid air. If the home has an IHS system, it can control a normal bathroom fan. This enables the timer duration to be freely selected using the IHS system’s software. The occupants can also choose not to let the fan run if the bathroom has only been occupied for a short time. For a longer occupation period, the fan will automatically start. After all, in that case there is a greater chance that someone is using the bath or shower.
  14. 14. Publication No Cu0257 Issue Date: April 2017 Page 11 8. KEEPING DRIVEWAYS AND FOOTPATHS FREE OF ICE This last section has nothing to do with the interior climate of the home. Allow us to step outside for a moment. Many homes have a driveway, a footpath or even one or more parking spaces. In the winter period, these areas can become dangerously slippery due to ice formation or snow. To minimise the chance of people falling, these areas can be fitted with an automatic heating system. In the interests of economy, de-icing the driveway can be restricted to those parts of the driveway that come into contact with the car’s tyres. 8.1. WORKING METHOD It is important to ensure the surface has sufficient drainage to allow the meltwater to flow away and not re- freeze. Electric cables are installed under the finished driveway. Their internal resistance causes them to heat up when a voltage is applied. Cables on a roll are available, but cable mats on a roll are much easier as the cables have already been installed at the correct distance from each other on braiding. A temperature sensor is also installed in the ground and this passes its measurements to a control unit to which the resistance cables are connected. The temperature at which the system must activate can be set on the control unit. If necessary, time blocks can prevent unnecessary energy consumption. Normal consumption is 270W/m². That lets the system react quickly enough and cause the ice to melt. Figure 9: On the left you can see the control unit that automatically keeps footpaths, driveways and parking spaces free of snow and ice. On the right you can see the temperature sensor that is installed in the ground. (Photo sources: OJ Electronics)

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