Intelligent Buildings Technology

1. Intelligent Buildings Technology

2. Introduction-Energy Management Energy used in buildings accounts for almost half of the total amount of energy consumed in the European Community today. Almost 85% of the energy used in buildings is for low temperature applications such as space and water heating. Appropriate building designs involving clean and efficient technologies are already available and there use may help to reduce future energy consumption as well as to provide a better quality of life for citizens. Intelligent Buildings Technology

3. Introduction-Energy Management With fossil fuels the primary energy source, the building sector currently produces 22% of total CO2 emissions in the EC. This is more than that produced by the industrial sector. Intelligently designed buildings are those that involve environmentally responsive design taking into account the surroundings and building usage and involving the selection of appropriate building services and control systems to further enhance building operation with a view to the reduction of energy consumption and environmental impact over its lifetime. Intelligent Buildings Technology

4. Energy in Buildings Buildings are inherently linked to their usage and surroundings and hence their indoor environment is the result of a range of interactions affected by seasonal and daily changes in climate and by the requirements of occupants varying in time and space. The design of buildings in the mid-late twentieth century has sought to eliminate the effect of outdoor daily and seasonal changes through the use of extensive heating, cooling, lighting and ventilation equipment, resulting in spiraling energy consumption and environmental impact. Intelligent Buildings Technology

5. Intelligent Buildings Technology Energy in Buildings • A more climate sensitive approach linked to the use of advanced control systems allows the building occupants to control their indoor environment whilst maximising the contribution of ambient energy sources to the creation of a comfortable indoor environment through the use of a more climate sensitive design approach. • Under almost all circumstances it is necessary at some point in time to provide some form of auxiliary heating, cooling, lighting or ventilation since natural sources cannot always cover the requirements for thermal comfort, visual comfort and IAQ that are the prerequisite for a well balanced, comfortable and healthy indoor environment.

6. Intelligent Buildings Technology Energy in Buildings • The purpose of energy management in buildings, and hence the role of the building energy manager, is to identify the areas in building stock where energy is used in excess. • Energy consumption in building is required for the following uses: • Heating • Cooling • Ventilation • Lighting • Equipment and machinery • Domestic hot water

7. Intelligent Buildings Technology Indoor Comfort • Thermal comfort • Visual Comfort • Indoor air quality

8. Thermal Comfort

9. Intelligent Buildings Technology Thermal Comfort • Comfort is defined as the sensation of complete physical and mental well being. • Thermal neutrality, where an individual desires neither a warmer nor a colder environment, is a necessary condition for thermal comfort. • The factors affecting comfort are divided into personal variables: • activity • Clothing • and environmental variables, • (air temperature, • mean radiant temperature • air velocity • air humidity

10. Intelligent Buildings Technology Thermal Comfort – Energy Balance

11. Intelligent Buildings Technology Thermal Comfort – Personal Variables • Clothing: describes the occupant’s thermal insulation against the environment. This thermal insulation is expressed in clo units.

12. Intelligent Buildings Technology Thermal Comfort – Personal Variables • Activity: The metabolic rate is the amount of energy produced per unit of time by the conversion of food. It is influenced by activity level and is expressed in mets (1 met = seated relaxing person).

13. Intelligent Buildings Technology Thermal Comfort – Environmental Variables • Temperature The average air temperature from the floor at a height of 1.1 m. • Mean Radiant TemperatureThe average temperature of the surrounding surfaces, which includes the effect of the incident solar radiation. • Air VelocityWhich affects convective heat loss from the body, i.e. air at a greater velocity will seem cooler. • Air HumidityWhich affects the latent heat losses and has a particularly important impact in warm and humid environments

14. Intelligent Buildings Technology Thermal Comfort – Indices • Although the four parameters of air temperature, radiant temperature, relative humidity and air movement are generally recognized as the main thermal comfort parameters, indoor environmental conditions in terms of thermal comfort can generally be assessed through three classes of environmental indices, namely: • Direct indices • Rationally derived indices • Empirical indices

15. Intelligent Buildings Technology Thermal Comfort – Indices • Direct indices • dry-bulb temperature • dew-point temperature • wet-bulb temperature • relative humidity • air movement • Rationally derived indices • mean radiant temperature • operative temperature • heat stress, and • thermal stress • Empirical indices

16. Intelligent Buildings Technology Thermal Comfort – PMV Index • The perceived need for both heating and cooling is to achieve accepted standards of thermal comfort, usually defined (directly or indirectly) by temperature limits. • Controversy exists as to what these standards of thermal comfort are. It has been observed that there has been an apparent discrepancy between comfort predictions using models derived from laboratory experiments, such as those by Fanger (1970), and subjective assessments of comfort found in field studies. It has been found – in a compilation of results from field studies in predominantly in warm and hot climates by Humphreys (1978) that the preferred comfort temperature in buildings was a function of the average monthly outdoor temperature (To is the mean monthly temperature):

17. Intelligent Buildings Technology Thermal Comfort – PMV Index • The Predicted Mean Vote (PMV) is a widely accepted mathematical expression of thermal comfort. This index is a real number and comfort is obtained if it lies within the specific limits of the comfort range. Since 1984, the index – which is calculated through a complex mathematical function of human activity, clothing and environmental parameters – has been the basis of the international standard ISO-7730. • This PMV is an index which predicts the mean value of the votes of a large group of people, and is directly related to the percentage of people dissatisfied (PPD), on the following seven point thermal sensation scale: + 3 Hot, + 2 Warm, + 1 Slightly Warm, 0 Neutral, - 1 Slightly Cool, - 2 Cool, - 3 Cold.

18. Intelligent Buildings Technology Thermal Comfort – PMV Index

19. Thermal Comfort – PMV Index The result of using Fanger’s equations seems to predict the need for much more closely controlled conditions than are usually found in free running buildings, in which people still seem to be comfortable. Some of the possible explanations for the apparent discrepancy between the prediction of the Fanger model and the findings of the Humphreys’ survey, are: The thermal comfort parameters, air temperature, radiant temperature and air movement vary spatially in a room, and the actual values experienced by an occupant may not be those described by a "room-average value". Thermal comfort parameters vary with time whereas the Fanger model predicts a response for steady conditions. The description of clothing level assumed in the use of the Fanger equation may not be the same as is actually worn in the real situation. The insulation value of the clothing may not be as predicted from the description of the clothing ensemble. The metabolic rate as assumed from the description of the activity may not be the same as the actual metabolic rate. Intelligent Buildings Technology

20. Visual comfort

21. Visual Comfort Visual comfort is the main determinant of lighting requirements. Good lighting provide a suitable intensity and direction of illumination on the task area, appropriate colour rendering, the absence of discomfort and, in addition, a satisfying variety in lighting quality and intensity from place to place and over time. People’s lighting preferences vary with age, gender, time and season. The activity to be performed is critically important. Various agencies (ASHRAE, CIBSE, etc.) and text books list optimal illuminances for different activities. These are generally based on uniform and constant levels of artificial light falling on the working plane. Intelligent Buildings Technology

22. Intelligent Buildings Technology Visual Comfort – Illuminance levels

23. Intelligent Buildings Technology Visual Comfort • Natural light is a fluctuating source of light. It depends on the hour of the day, the season, the climate and the latitude of the location. • The objective of a daylight technique consists of providing the best possible indoor luminous environment as often as possible. • A luminous environment should be appropriate to the function of the room: there should be enough light for reading, writing, or filing documents. • Illuminance of 300 to 400 lux on a desk are often considered as minimum required levels for most of office tasks. Hallways might require lower levels, 100 lux, and commercial centres higher levels, 700 lux. These requirements are defined by CIE. • Performance does not depend only on these illuminance levels. The location of the source of light with respect to the direction of observation may require higher illuminance, for instant when the observer faces a window.

24. Intelligent Buildings Technology Visual Comfort • The luminous environment should be comfortable, which means that sources of glare should be avoided. • Oversized glazed windows with clear glazing are sources of glare, and this can be fought in using multiple apertures, if possible on different walls. • Glossy materials and inappropriate shading devices might bring excessive amount of light in the field of vision. • Also, psychological aspects such as the quality of the vision to the outside, the beauty of the design and the attractiveness of the space are very important.

25. Intelligent Buildings Technology Visual Comfort Natural light comes from three directions: • Direct Sunlight • Diffuse light from the sky, and • Light Reflections from the Environment

26. Intelligent Buildings Technology Visual Comfort • The daylight factor is a measure of the daylight level at any position indoors as a percentage of the illuminance levels outdoors. The daylight factor at any point on a working plane is calculated in terms of light coming directly from the sky (the sky component), light reflected from outdoor surfaces (the externally reflected component) and light reflected form surfaces within the room (the internally reflected component). The average daylight factor in a space can be calculated from:

27. Intelligent Buildings Technology Visual Comfort – Indoor lighting distribution

28. Intelligent Buildings Technology Visual Comfort • If a predominately daylit appearance is required, then the daylight factor should be 5% or more if there is to be no supplementary artificial lighting, or 2% if supplementary lighting is provided. • Discomfort is caused when the eye has to cope with, simultaneously, great differences in light levels, the phenomenon we know as glare. Maximum recommended values for the ratio between different parts of a visual field, the luminance ratio, as shown in the following table.

29. Indoor air quality

30. Indoor air Quality A conflict has always existed between adequate ventilation and energy costs has long existed. During the last three decades, decreased ventilation rates for energy conservation, along with increased use of synthetic (i.e. man-made) materials in buildings have resulted in increased health complaints from building occupants. However, energy efficiency and good indoor air quality in buildings need not be mutually exclusive. Good indoor air quality is a function of a number of parameters including: the initial design and continuous maintenance of HVAC systems; use of low toxic emittance building materials; and consideration of all sources of indoor air pollution such as occupant activities, operation of equipment and use of cleaning products. In fact, in 1986 the WHO (World Health Organisation) reported that "energy-efficient but sick buildings often cost society far more than it gains by energy savings". The result of the reductions in ventilation rates in buildings have led to the so called "Sick Building Syndrome" (SBS) and "Building Related Illness" (BRI). Intelligent Buildings Technology

31. Indoor air Quality – Indoor pollutants Every building has a number of potential sources of indoor air contaminants. Some sources, such as building materials and furnishings, release contaminants more or less continuously. Other sources are related to occupant activities and therefore release contaminants intermittently. Such activities include cooking, smoking, use of solvents, pesticides, paint, and cleaning products, and operation of office machines and equipment. High concentrations of pollutants can remain in the indoor air for long periods after they are emitted. Although some sources may be common in all building types, office and commercial buildings vary greatly from residential buildings in terms of design, air handling systems and occupant activities and therefore certain indoor air pollutant sources may be more prevalent in some types of buildings. Intelligent Buildings Technology

32. Indoor air Quality – Ventilation There are two types of ventilation: natural and mechanical. Natural ventilation includes the movement of outdoor air through intentional openings such as doors and windows and through unintentional openings in the building shell scuch as cracks which result in infiltration and exfiltration. Mechanical or forced ventilation is intentional ventilation supplied by fans or blowers. These fans are usually part of the buildings HVAC system which heats, cools, mixes and filters the air being supplied to the building. Intelligent Buildings Technology

33. Intelligent Buildings Technology Climate

34. Intelligent Buildings Technology Climate • Climate responsive design in buildings takes into account the following climatic parameters which have direct influence on indoor thermal comfort and energy consumption in buildings: • The air temperature, • The humidity, • The prevailing wind direction and speed, • The amount of solar radiation and the solar path. • Long wave radiation between other buildings and the surrounding environment and sky also plays a major role in building performance.

35. Intelligent Buildings Technology Climate • The outdoor air temperature has a significant effect on building thermal losses due to conduction through the walls and roof of the building, as well as affecting ventilation and infiltration losses due to either desirable or undesirable air changes. • In warm climates the relative humidity plays an important role in determining thermal comfort levels, since during warm weather the high pressure of water vapour prevents the evaporation of perspiration from the body thereby inhibiting the body from being maintained at a comfortable temperature.

36. Intelligent Buildings Technology Climate • Prevailing wind speed and direction affect significantly the building thermal losses during the heating season, increasing both convection at exposed surfaces and hence encouraging envelope losses and also by increasing the air change rate due to natural ventilation and infiltration. During the cooling season, the knowledge of both the direction and wind speed permits the design of the building to facilitate passive cooling. • The sun-path and the cloud cover determine the amount of solar radiation impinging on differently inclined surfaces and since the sun-path changes from season to season, so does the amount of direct solar radiation impinging on these different surfaces.

37. Intelligent Buildings Technology • Macroclimate is a term referring to the general climatic character of a region in terms of temperature, humidity, precipitation, wind, sunshine and cloud cover. An appreciation of the overall characterisation of the climate of a region is a fundamental requirement for climate responsive building design, this affecting the general design principles which should be followed. • Regional climatic factors are strongly affected by the local topography, vegetation and the nature of the area, resulting in deviations from the regional macroclimate. The effect of such factors results in climatic characteristics known as the mesoclimate. Heavily vegetated or densely built-up areas have a significant impact on the climate of a specific location. • The conditions of the climatic parameters of a specific site or around a building are termed the microclimate. Temperature, humidity, wind speed, and solar radiation around a building can be affected by the deliberate placement of vegetation, landscaping, water and fountains, and positioning of constructions

38. Intelligent Buildings Technology Building – Climate interaction

39. Intelligent Buildings Technology Building Envelope • The building envelope responds dynamically to the impact of the outdoor climate on the envelope exterior and the effect of the occupancy pattern and building usage on the interior. • However, the performance of the heating, ventilation and air-conditioning systems, artificial lighting, fenestration opening and shading can be harmonized and optimized in response to occupancy needs and climatic conditions through a building energy management system which allows direct control of the necessary actuators either manually or automatically. • In this manner the individual components of the building can be controlled to produce the best possible indoor environment with minimum energy consumption.

40. Intelligent Buildings Technology Heat transfer • Conduction - C • Radiation - R • Convection - C

41. Heat transfer Conduction Conductive heat transfer is a process by which thermal energy is transmitted by direct molecular communication. It is the only mechanism by which heat flows in an opaque solid. Conduction in a translucent solid is accompanied by radiation, whilst heat transfer through stagnant gases and liquids takes place by conduction with some radiation. Convection enhances the thermal equilibrium process in moving fluids. The thermal conductivity k of a substance determines its ability to conduct heat. Conductive heat transfer with respect to buildings concerns the heat losses through the building envelope: the walls, windows and doors. Heat transfer is caused by a temperature difference across the envelope, always in the direction of the temperature gradient, with energy entering the one surface at a higher temperature and leaving the other surface at a lower temperature. Therefore, buildings are generally affected by envelope losses in the winter and envelope gains in the summer. Intelligent Buildings Technology

42. Intelligent Buildings Technology Heat transfer Conduction

43. Heat transfer Convection Convection is a process of heat transfer by the combined action of heat conduction, energy storage and mixing motion. Convection is combined to fluids only and requires an external force -either forced or natural (buoyancy)- to be present. The rate of heat transfer depends on the temperature difference between the fluid and the surface and the convective heat transfer coefficient h. The convective heat transfer co-efficient is a function of 1) the geometry of the system, 2) the velocities and mode of fluid flow, 3) the physical properties of the fluid and 4) possibly on the temperature difference. The convective heat transfer is therefore not constant or uniform over the whole surface, although for all intensive purposes in building physics it is often considered to be so. Intelligent Buildings Technology

44. Intelligent Buildings Technology Heat transfer Convection

45. Intelligent Buildings Technology Heat transfer-Radiation • All bodies emit radiation. Heat transfer via radiation occurs when a body converts part of its internal energy (a result of its temperature) into electromagnetic waves. • In buildings heat transfer due to radiation is most apparent with transparent elements, where a large amount of the impinging radiation coming from the sun is transmitted to the building material. • Radiative heat transfer can also contribute to the cooling of external surfaces through exposure to the night sky, wherin these surfaces emit net radiation towards the clear sky, or in the effect of discomfort associated with sitting next to hot or cold surfaces (i.e. cold windows).

46. Intelligent Buildings Technology Heat transfer-Radiation

47. Intelligent Buildings Technology Thermal storage • The ability of a material to store energy is characterised by its specific heat (cp, J/kgK). The specific heat of a material is defined as the amount of heat necessary to raise a unit mass of the material by one degree. The heat that is stored in the mass of the material, m, for a temperature change, ΔT, is given by:

48. Intelligent Buildings Technology Energy Management Systems

49. Intelligent Buildings Technology Intelligent Building-Definitions • EIBG (European Intelligent Building Group): One that incorporates the best available concepts, materials, systems and technologies integrating these to achieve a building which meets or exceeds the performance requirements of the building stakeholders, which include the owners, managers and users, as well as the local and global community. • Also from EIBG but more often quoted: One that maximizes the efficiency of its occupants and allows effective management of resource with minimum life costs

50. Intelligent Buildings Technology Intelligent Building-Definitions • IBI (The Intelligent Buildings Institute in Washington DC, US): one that provides a productive and cost-effective environment through optimization of its four basic components - structure, systems, services and management - and the interrelationships between them.