Comfort Factors in Buildings
72
Introduction
2
Visual Comfort
2-6
Ventilation and air quality
6-7
Acoustics comfort
7-10
Condensation
0-12
Thermal Comfort
2-13
Conclusion
3
References
4
Bibliography
4
INTRODUCTION
Buildings are basically constructed to provide security, shelter, warmth and light for occupants. These necessitates were fundamentally met by a cave with a fire. In the present time, after the basic needs are supplied, the new demand will be a sophisticated and comfortable internal environment with more facilities. Several factors should be taken into account trying to "provide and maintain" a comfortable environment for occupiers such as a comfortable work, living, leisure environment for people and an adequate environment for machinery and equipment which requires the right conditions to operate.
However comfort is very subjective and differs from occupier to occupier because people have different comfort levels. The aim of designers should be to make the greatest number of occupier happy and minimise discomfort.
Comfort factors are related to our senses, touch, vision, smell and hearing. A building should provide and maintain a good visual and aural environment and an ambient temperature also including no unwanted noise or smell, efficient and good lighting, fresh air, warmth or cooling. Design criteria should consist of all these factors. However the choice of materials depends on several issues such as, age of occupiers, level of activity of occupiers, use of space etc.
Key environmental Factors:
a) VISUAL COMFORT
To be able to see well enough in buildings is a fundamental need for occupants to do their work safely and comfortably or live comfortably in a pleasant environment. There should be efficient lighting provided which is not rather bright, nor rather dull. Glare will be caused if there is a big bright source of light and will give occupiers visual discomfort and might cause visual disability.
Efficient light is measured in lumens/m² or lux and generally described in terms of the illuminance which is the amount of light reaching a surface. A domestic 60W light bulb emits approximately 700 lumens. Different illuminance is required to do different tasks from moving around safely to do restoration work on a painting or using a sewing machine.
Designers should take quality of light and quantity of light into account for good lighting. Elements regarding quantity consist of illumine (the amount of light) and distribution of light (spacing, layout and luminaire type,) Elements regarding quantity include contrast, colour, glare. Additional factors which influence visual comfort are veiling reflections and highlights, shadows and flicker.
Glare can be caused by bright light or excessive dazzle or reflection. Well designed lighting should eliminate glare.
Bright light within the field of view like a bright lamp or a sunlit window can result in glare either as a direct source or by reflection such as glare on computer.
Effects of glare:
* "Disability glare occurs when vision is impaired by excessive dazzle form a bright light source such as light reflecting from a glossy surface" (Source: CIBSE Knowledge Series, Comfort)
(www.fsec.ucf.edu/.../windows/how/glare.htm)
* "Discomfort Glare, where visual discomfort is caused by very bright light such as direct sun light or bright lamps" (Source: CIBSE Knowledge Series, Comfort)
(www.fsec.ucf.edu/.../windows/how/glare.htm)
Illuminance necessities should be regarding to the task, highest levels only for the immediate task areas and lower levels as appropriate for the surrounding areas and lower still for circulation areas.
Building /room type
Maintained illuminance (lux) at the appropriate working plane or height
Notes
Dwellings
* Bathrooms
50
* Bedrooms
00
Study bedrooms require 150 lux at desk
* halls, stairs
00
* kitchen
50-300
* Living rooms
50-300
Offices
* Conference/board rooms
300-500
* Computer rooms
500
* Corridors
00
* Drawing office
750
* Entrance halls and lobbies
200
* General office space
300-500
* Open plan
300-500
* Toilets
200
Retail
* Department stores
300 for circulation areas
Higher lighting levels at checkouts and tills and for display lighting
* Small shops
300 for circulation areas
* Supermarkets
400 for circulation areas
* Shopping malls
50-300
Schools
* Teaching spaces
300
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300-500
* Computer rooms
500
* Corridors
00
* Drawing office
750
* Entrance halls and lobbies
200
* General office space
300-500
* Open plan
300-500
* Toilets
200
Retail
* Department stores
300 for circulation areas
Higher lighting levels at checkouts and tills and for display lighting
* Small shops
300 for circulation areas
* Supermarkets
400 for circulation areas
* Shopping malls
50-300
Schools
* Teaching spaces
300
(Source: CIBSE Knowledge Series, Comfort)
Building Regulations
. "Light fittings including lamp, control gear, housing, reflector, shade, diffuser or other device of controlling the output light should only take lamps with a luminous efficiency greater than 40 lumens per circuit-watt"
2. "Fixed energy efficiency light fittings (one per 25m² dwelling floor area [excluding garages] and one per four fixed light fittings) should be installed in the most frequented locations in the dwelling.
3. "All areas that involve predominantly desk-based tasks(i.e. such as classrooms, seminar and all conference rooms- including those in schools) shall have a average efficiency of not less than 45 luminaire-lumens/circuit-wall (averaged over the area)"
(Source: Building Regulations in Brief)
Lighting costs are generally 15-20 % of the electricity bill at residential dwellings. Fitting low-energy lighting such as compact fluorescent lamps (CFLs) is a simple but a very cost-effective way of saving energy if they are used in the most used rooms such as kitchen or living room. Good quality CFLs which consist of 'high-frequency ballasts' do not flicker or light up suddenly. (Source:www.energysavingtrust.org.uk)
By increasing the window size and area in a building thus increasing the amount of natural light produces a more comfortable living and work environment and reduces the need for artificial light and associated costs there of. Ideally buildings should be north south facing to maximise the amount of natural daylight.
My house for example has a south facing rear aspect thus enjoying natural daylight from dawn until dusk to the rear of the building. The main rooms in the house ie. Lounge, kitchen, main bedroom and bathroom are south facing maximising the natural daylight. French windows to the lounge give floor to ceiling natural light. Double doors to the kitchen again offer floor to ceiling natural light. We also use low energy lighting throughout the house with lamps having 8 times the life of old filament lamps.
b) VENTILATION AND AIR QUALITY
Definition of ventilation in Building Regulations is "the supply and removal of air (by natural and/or mechanical means) to and from a space or spaces in a building"
Additionally ventilation is used for accomplishing adequate air quality and extracting water vapour from wet areas such as bathrooms and kitchens in buildings. Air quality is judged firstly by smell, the symptoms of smoke, pollens or pollution are irritation to eyes, nose or throat.
Fresh air is needed for comfort to supply oxygen for respiration (0.2 litre/s per person). Additionally ventilation is a way of controlling thermal comfort. Approved Document F of Building Regulations emphasises that designers of a building are free to make a choice over the type of ventilation system for a specific building on the condition that the system meets the requirements and standards.
As Approved Document F 1.5 demands utility rooms, all kitchens and sanitary rooms must be provided with an extraction fan which is linked to the outside of the property.
"There shall be adequate means of ventilation provided for people in the building.
Requirement: Ventilation (mechanical and/or air-conditioning systems designed for domestic buildings) shall be capable of restricting the accumulation of moisture and pollutants originating within a building."(Building Regulations, part F-Ventilation.)
In the case of having contaminants in buildings, such as odours or pollutants from a manufacturing process, eg. paint or glue, the amount of fresh air supply provided has to be assessed under the Control of Substances Hazardous to Health Regulations 1994"
Any ventilation systems installed should not cause a disturbance for the occupiers of the property on the account that it might affect their health, concentration or work effectiveness.
All replacement windows should include trickle ventilators or have an equivalent background ventilation opening to the same room (Approved Paper F 3.4, Building regulations)
For instance each room in my house has adequate opening windows to provide ventilation as required. With double glazed units installed incorporating trickle vents to the top of the frame. Electrical mechanical ventilation to kitchen, bathroom and shower room, activated via light switch with run-on timer ensures minimising condensation problems and expelling odours.
c) ACOUSTICS COMFORT (AURAL COMFORT)
Noise can be simply identified as unwanted sound.
The principal necessity of acoustic comfort is an efficiently quite environment which enables occupants to fulfil their tasks in a comfortable environment without distraction of noise or vibration.
"Sound is a vibration or pressure wave that moves through a suitable medium such as air or structure at a frequency and intensity that can be detected by the human ear" (CIBSE knowledge Series: Comfort) Sound level is measured by decibel (dB).
Airborne sound, that which travels through the air and can be heard by the human ear.
The unwanted sound which comes from an external source may enter a building through the open windows and additionally through cracks and gaps in the structure and may be transferred through the ventilation ductwork and ceiling voids. Airborne sound can be reduced by use of mass to insulate the noise transmission routes. A single leaf brick wall will provide better sound insulation than a single leaf lightweight partition. On the other hand double leaf partitions can give improved sound insulation provided both leaves are insulated properly.
Structure borne sound occurs when vibrations from a source travel via solid structures and is heard and felt, such as machinery on a concrete floor.
There are three effects of noise which are annoyance - when unwanted sound can influence occupants' concentration while they perform their tasks, masking - when a wanted sound is covered by an unwanted sound (such as a teachers voice cannot be heard by students due to traffic noise) and hearing damage - when unbearable sound affects people's hearing temporarily or sometimes permanently.
As an example our house is located on a main road in Bromley town centre and was built in 1923 with solid double walls with no cavity, but the density of the brick work provides excellent sound insulation. In tandem with the double glazing sound proofing is maximised.
A property we manage is in a four storey block, which has concrete floors with minimum sound insulation. After a number of complaints by other occupiers due to unbearable noise transfer, the laminate-wooden flooring fitted previously to the concrete subfloor has been removed and replaced with good underlay and carpet to provide a comfortable environment.
Building regulations
Part E-resistance to the passage of sound
Number
Title
Regulation
Requirement
E1
Protection against sound from other parts of the building and adjoining buildings.
Dwelling-houses, flats and rooms for residential purposes shall be designed and constructed in such a way that they provide reasonable resistance to sound from other parts of the same building and from adjoining buildings.
dwelling shall be designed so that noise from domestic activity in an adjoining dwelling 9or other parts of the building) is kept to a level that:
-does not affect the health
-will allow them to sleep, rest and engage in their normal activities in satisfactory conditions.
E2
Protection against sound within a dwelling-house etc.
Dwelling-houses, flats and rooms for residential purposes shall be designed and constructed in such a way that: (a) internal walls between a bedroom or a room containing a water closet and other rooms, and (b) internal floors, provide reasonable resistance to sound.
E2 does not apply to:
-an internal wall which separates an ensuite toilet from the associated bedroom
-an internal wall which contains a door
-existing walls and floor in a building which is subject to a material change of use.
E3
Reverberation in the common internal parts of buildings containing flats or rooms for residential purposes
The common internal parts of buildings which contain flats or rooms for residential purposes shall be designed and constructed in such a way as to prevent more reverberation around the common parts than is reasonable.
Suitable sound absorbing material shall be used in domestic buildings so as to restrict the transmission of echoes.
E3 only applies to corridors, stairwells, hallways and entrance halls which give access to the flat or rooms for residential purposes.
E4
Acoustic conditions in schools
Each room or other space in a school building shall be designed and constructed in such a way that it has the acoustic conditions and the insulation against disturbance by noise appropriate to its intended use.
(Source: Building regulations in Brief)
Offices
Criterion
Typical situations
Design range
LAeq,T (dB)
Good
Reasonable
Reasonable conditions for study and work requiring concentration
Library, cellular office, museum
40
50
Staff room
35
45
Meeting room, executive office
35
40
http://www.workplacelaw.net
d) CONDENSATION
Condensation is still a serious problem in buildings in spite of all the improvements happening in the damp proofing industry.
Condensation occurs when air carrying moisture comes into contact with a colder surface. Condensation can be noticed on a non-absorbent surface such as tiles or windows. Sometimes it can occur on other surfaces but not noticed until mould starts growing or materials start rotting.
In the UK, condensation in properties gets worse in winter when warm moist air in living areas makes its way to the colder parts of the building.
The moisture of air occurs due to various sources inside the properties such as breathing, cooking, washing and drying, heating etc. The results of moisture generated become worse when it is kept in the properties. The easiest and basic way to avoid condensation is providing adequate ventilation especially in wet areas such as bathrooms and kitchens, where a great quantity of moisture is produced.
Condensation often occurs in properties with single glazed windows in the UK. Although it is not possible to get rid of all condensation, having secondary glazed windows with adequate ventilation reduces the amount of condensation generated within the property.
A properly insulated roof space should not be affected by condensation.
Properties should have a damp proof course (DPC) which avoids soil moisture from rising up to the living or working areas which can result in several problems such as damage or decay of building materials, health problems or discomfort of occupiers.
It should be emphasised that the main ways of controlling condensation are insulation ventilation and heating.
Approved documents C, F and J are related to condensation including ventilation. There are also building regulations regarding external doors, floors and roofs on this matter.
]
www.buildingconservation.com
Without adequate ventilation condensation always creates a problem is wet areas. Properties that we manage often suffer from bad condensation which is due to the tenants not understanding that bathroom, shower and kitchens require adequate ventilation to disperse the humidity caused by their function. To prevent drafts we often find the vents have been covered over and windows not left ajar. The airborne water clings especially to tile joints and produces damp spores, painted walls in these areas also suffer from the problem.
Often vent bricks installed in properties at low level to ventilate ground floor timbers become blocked and the circulation of air is restricted and this leads to wet rot turning to dry rot.
I have no condensation problem at my house due to having adequate secondary glazing, ventilation, heating and insulation.
e) THERMAL COMFORT
Thermal comfort is rather difficult to define due to the number of personal and environmental factors which should be taken into account during the design process. Because thermal comfort is related to psychology of occupants and comfort levels are subjective, it is impossible to make all people happy thus the aim should be to make the majority of occupants thermally comfortable in an environment. Basically thermal comfort is when occupants are satisfied with the environment they occupy in the buildings.
In buildings the fundamental internal environmental elements are humidity, temperature, air quality and air movement, which depend on the design of the building and the operation of the building services, the use of the space and the external weather conditions.
To be comfortable a balance between heat loss and gain should be achieved, ie if the surrounding temperature is too high, the body is too hot and uncomfortable. Conversely if the surrounding temperature is too cold, the body becomes cold and again uncomfortable. Therefore equilibrium of temperature is necessary for thermal comfort.
At the planning stage, the heat and ventilation criteria should be established. "A typical initial design condition might therefore be written as 21C and 50 %RH for operative temperature and relative humidity respectively with 10 lt/s per person of fresh air required." ((CIBSE knowledge Series: Comfort)
The latest regulations demand that insulation of buildings, which entails cavity wall insulations, double glazing, loft insulation and H.E. boilers, slab insulation, E factor glass on windows are all necessary. With such and emphasis placed on reduction in consumption of natural energy, gas and electricity, the insulation forum has a high priority.
(Cavity wall-Source:http://www.energysavingtrust.org.uk)
CONCLUSION
It is important to bear in mind the comfort requirements and needs at an early stage of the design process and providing a system to achieve these requirements efficiently. But while trying to achieve this goal, designers should consider the cost and complexity of systems they design. A rather expensive and a complicated system which occupants would find difficult to operate cannot be called a success.
REFERENCES
* Race, G.L (2006) CIBSE Knowledge Series, Comfort. 1st edition. CIBSE Publications.
* Tricker, Ray and Algar, C (2005) Building Regulations in Brief. 7th edition. Elsevier.
* Hall, F (1997) Building Services and Equipment. 2nd edition. Pearson
* Brinkley, M (2004) House Builder's Bible. 6th edition. Ovolo Publishing.
* Hall, Fred and Greeno, R (2005) Building Services Handbook Incorporating Current Building and Construction Regulations. 3rd edition. Elsevier.
BIBLIOGRAPHY
* http://www.buildingconservation.com. Articles. Available from
http://www.buildingconservation.com/articles/condensation/condensation.htm
[Accessed: 2 November 2007]
* Condensation. Available from
http://www.diydata.com/problem/condensation/condensation.php
[Accessed: 29 October 2007]
* Glare. Available from
http://www.fsec.ucf.edu/en/consumer/buildings/basics/windows/how/glare.htm
[Accessed: 1 November2007]
* Cavity Wall. Available from
www.energysavingtrust.org.uk)
[Accessed: 1 November2007]
* Work Place Work Law. Available from
http://www.workplacelaw.net
[Accessed: 1 November2007]
HNC-YEAR1
Construction Technology and Building Design
