The Code for Sustainable Homes was introduced in England in April 2007, and sets a single national standard within which the home building industry can design and construct homes to a higher environmental standard, giving new home buyers better information about the environmental impact of their new home and potential running costs. Sustainability is high on the Government agenda as it is not sustainable to continue with the inefficiencies and carbon omissions created by the design of builds in the past.
In this assignment I aim to analyse the living area within a three floor four bedroom detached house, which was built in 1969. I will look at and analyse the built environment in respect of thermals, ventilations, acoustics, light and Air Flow, making recommendations as to how changes would increase efficancy or impact more positively on the environment.
Light
There are various sources of light to any building e.g. natural light, daylight, sunlight, artificial light, up light, and spot lights. Light is important to ensure the building and its occupants can function adequately, and the right light levels for the room and it’s use can increasing the functionality of the space considerably.
The living room’s biggest source of light is natural light gained through two very large double patio doors. There are benefits to this natural light, in that it is preferred by people, and provides a nice view of the garden and beyond, which includes fields and open space. It also reduces the need for artificial light, thus saving energy. However, on a negative side, it leads to too much heat gain & glare from the sunlight in the Summer. This means curtains often have to be closed to cool the room and avoid glare which affects use of tv, computer screens etc, thus losing the benefit of the natural light. The excessive sunlight also has implications because it causes damage to furniture e.g. bleaching wooden floor, drying leather, changes colour of gloss/paint etc.
Below example of excessive sunlight
The large patio doors also have maintenance cost implications. UVPC windows only last about 10 years, and have to be replaced. Brick work would not need replacing this often.
Thermals
Heat energy and other thermal properties are essential in maintaining human body comfort, and therefore, they play a major role in the performance of buildings. Thermal insulation is very important in reducing heat loss from buildings, and so insulation is the basis of a good design. Insulation, which is relatively cheap, can produce cost savings in terms of fuel savings and carbon omissions for the life of the building.
Part L of the Building Regulations sets out minimum standards for thermal performance of a building. Approved Document L1A lists limiting U-values for the building fabric. The Approved Document also sets out criteria for air permeability, heating and hot water systems, insulation of pipes, ducts and vessels and lighting.
The u-value measures how well a building component e.g. a wall, roof or a window keeps the heat inside a building. U-values are also important measures in warm climates, as u-values are an indicator of how the inside of a building can be kept cold. The higher the U-value the more heat flows through so a good U-value is a low one as you want to keep the heat inside or outside, depending on the climate you live in. The table below sets out the average weighted u-value which should not be exceeded.
The house I am evaluating doesn’t meet current building regulations, as it was built in 1969, and Building Regulations at that that time would not require builders to meet the same standards as they do today.
On calculating the U-value of the standard cavity wall with no insulation (table 1) and comparing it with a cavity wall with wool insulation, there is a vast difference in the U-value. This shows that heat loss and gain could be greatly reduced if the existing cavity walls were injected with insulation.
Table 1
Layer Thickness (mm) Conductivity (W/m.K)
Outer leaf 100 1.21
Air space 50 r = 0.18
Inner leaf 100 0.30
Internal finish 13 0.57
U-value of the wall = 1.33
Table 2
Layer Thickness (mm) Conductivity (W/m.K)
Outer leaf 100 1.21
Cavity ins 100 0.032
Inner leaf 100 0.30
Internal finish 13 0.57
Area of wall ties: 12.5 mm�
Wall ties per square metre: 2.5 /m�
Conductivity of wall ties: 17 W/m�K
U-value of the wall = 0.27
The property has UVPC double glazed doors and windows. They are 16mm Arogon filled glass. The U-value is 2.6 which is in line with current building regulations, but could be improved by using the more modern Pilkington Glass which has a lower u-value, and reflects the sunlight out of the room, and the head back into the room.
Another option to reduce heat gain in the summer and reduce heat loss in the Winter would be to remove one of the patio doors and replace it with an insulated cavity wall. Insulated cavity walls have a much lower U-value than glass. However, this would involve significant work, and would alter the look of the property.
Air Flow
In any occupied space there is a need for ventilation to remove contaminated air and to provide oxygen. We need oxygen for life. If humans are to feel comfortable inside a building, then there needs to be fresh air at the correct temperature, with the right amount of moisture, and free from pollutants and odours. Mcmullan (2007) p 72
It is important through, to ensure that a balance is struck between getting rid of stale air, and keeping energy in the building.
If buildings are not adequately ventilated there will be excessive carbon dioxide, build up of smells and odours, excessive heat, combustion of productions for heating and cooking etc.
As cited by Mcmullan (2007) p73 there are a number of regulations that ensure buildings are adequately ventilated. These include, Building Regulations, Workplace regulations, housing acts and Healthy and safety at work regulations.
Mucmullan (2007) p74 sets out the methods of ensuring minimum ventilation “as used by the building regulations include the following:
- number or area of open windows to provide rapid ventilation;
- area of opening to provide trickle ventilation;
- performance of fan or stack to provide extract ventilation”
The ventilation in the living area is natural, provided by opening patio doors and windows. In addition there is trickle ventilation at the heads of the windows to ensure adequate ventilation at times when the property is unoccupied or it is too cold to open windows and doors. The kitchen is adjacent to the living area, and has mechanical fans to aid ventilation. The use of mechanical ventilation makes it possible to use spaces, such as those deep in the building and without natural ventilation.
One of the objectives of effective ventilation is to avoid condensation. Mucmullan (2007) p 87 describes condensation as “a form of dampness caused by water vapour in the air.” The effects of condensation is dampness and mould growth, misting of windows, and beads of water on non absorbent surfaces. Condensation isn’t a normally a problem in rooms in which the design has given condensation is expected, for example, kitchens and bathrooms, as the building design includes things like tiles, and mechanical fans. However, condensation is a recent concern in newer buildings. Condensation is not an issue in the living area I am analysing, and this is because heating, ventilation and insulation is adequate.
Acoustics
Due to the property being situated only a minute walk from Biggin Hill airport it can get very noisy. Sound reduction could be improved by replacing double glazing with triple witch would also reduce the u-value also wool filled cavity could reduce noise pollution.
There are two main types of noise transfer
- Airborne sound (sound that travels through the air before reaching a partition.)
Sources of airborne sound are aircraft traffic, vehicles, radios, voices musical instruments.
- Impact sound (sound generated from a partition.)
Sources of impact sound are doors, footsteps, switches
This table lists the Absorption coefficients of some of the materials in the room.
Floor materials
125Hz
250Hz
500Hz
1 kHz
2 kHz
4 kHz
Wood parquet on concrete
0.04
0.04
0.07
0.06
0.06
0.07
Reflective wall materials
125Hz
250Hz
500Hz
1 kHz
2 kHz
4 kHz
Brick (natural)
0.03
0.03
0.03
0.04
0.05
0.07
Concrete block (coarse)
0.01
0.01
0.02
0.02
0.02
0.03
Glass (1/4″ plate, large pane)
0.18
0.06
0.04
0.03
0.02
0.02
Plaster (gypsum or lime, on masonry)
0.01
0.02
0.02
0.03
0.04
0.05
Ceiling material
125Hz
250Hz
500Hz
1 kHz
2 kHz
4 kHz
Plasterboard (12mm(1/2″) in suspended ceiling grid)
0.15
0.11
0.04
0.04
0.04
0.04
Conclusion
There are clearly strong moves towards sustainability, and increased requirements for developers to ensure buildings become increasingly environmentally friendly and are efficient to run. Looking at a building built in the 1960’s it is clear how things have changed over the years, and as identified in my assignment there are things that could be done to increase efficacy and sustainability.
