Context analysis, Sun and Daylight Analysis, Wind Analysis and Simulation, Venti-lation
A contextual analysis is a research activity that looks at the existing conditions of a pro-ject site, along with any imminent or potential future conditions. The purpose is to inform us about a site prior to the start of our design process so that our initial design thinking about a site can incorporate considered responses to the external conditions.
An architectural site analysis will look at issues such as site location, size, topography, zoning, traffic conditions and climate. The analysis also needs to consider any future de-velopments, or changes to the sites surroundings, such as a change of roads designa-tions, changing cultural patterns, or other significant building developments within the area.
Understanding the context of a site is key to enabling the designer to weave the new de-sign in with the existing fabric of the site. It allows us to understand the existing opportu-nities, or problems in a site, and make informed decisions on how to respond to our find-ings. This response could be that the designed building reflects the surrounding context and is designed to be in sympathy, or perhaps to turn away or eliminate certain un-wanted site conditions.
Our analysis data can be split into two main categories. Hard data and soft data.
Soft data looks at site conditions that can be changed. Hard data looks at more concrete elements such as site boundaries, site areas, utility locations, contours, dimensions, site features, climate, legal information. Early site investigations should look at hard data. From this, we are able to establish which elements we consider to have a negative im-pact on the site or proposed design and which conditions have a more positive influence. This allows us to create a hierarchy and gives a more systematic approach to under-standing our data and developing the design.
The general categories of data we will be looking at as we carry out our architectural site analysis are:
• Location – where the site is situated
• Neighbourhood context – the immediate surrounding of the site including data on zoning and buildings and other impacts on our project.
• Zoning and size – dimensional considerations such as boundaries, easements, height restrictions, site area, access along with any further plans.
• Legal information – ownership, restrictions or covenants, council related infor-mation, future urban development plans.
• Natural physical features – actual features of the site such as trees, rocks, topog-raphy, rivers, ponds, drainage patterns.
• Man made features – existing buildings, walls, surrounding vernacular, setbacks, materials, landscaping, scale.
• Circulation – Vehicle and pedestrian movements in, through and around the site. Consider the timing of these movements, and duration of heavier patterns. Future traffic and road developments should also be considered.
• Utilities – Any electricity, gas, water, sewer and telephone services that are situ-ated in or near the site, along with distances, depths and materials.
• Climate – all climatic information such as rainfall, snowfall, wind directions, tem-peratures, sun path, all considered during the different times of the year.
• Sensory – this addresses the visual, audible and tactile aspects of the site, such as views, noise, and so on. These again should be considered in time frames and a positive or negative factor can be attributed to the condition.
• Human and cultural – the cultural, psychological, behavioural and sociological as-pects of the surrounding neighbourhood. Activities and patterns, density, popula-tion ethnic patterns, employment, income, values and so on.
Good levels of daylighting are crucial to occupant comfort in new buildings.
The provision of daylight is as important as ensuring low levels of noise, or low levels of odour in maintaining the enjoyment of a property. Adequate levels of daylight are
important not only to light and heat the home, but also for an occupant’s emotional well-being.
Daylight is widely accepted to have a positive psychological effect on human beings and there is a great deal of evidence to suggest that people who are deprived of daylight are more susceptible to depression and mood swings. This is common in northern countries, such as Norway, Iceland and Canada where daylight is scarce during the winter months.
Daylighting calculations are often assessed alongside a Sunlight Analysis, which uses different criteria.
Solar modelling enables us to understand and control the geometric relationship between the sun and buildings.
Why do I need daylight calculations?
Daylighting analysis is commonly required:
• Because the designers would like to mitigate against poor levels of natural light
• For a Home Quality Mark assessment
• For a BREEAM Assessment
• Because a planning application requires them
Daylighting and Sunlight tests are routinely required by planning authorities across the UK and address potential light issues which may affect both the daylight and sunlight provision within a proposed new development and also the impact on neighbouring properties
Day light report will typically contain the following tests:
• Average Daylight Factor
• Daylight Distribution (No Sky Line)
• Room Depth
• Annual Probable Sunlight Hours
• Overshadowing to Gardens and Open Spaces
What is wind analysis?
A wind analysis is a planning submission requirement, which provides a visual model and a written evaluation of how a proposed development will impact pedestrian-level wind condi-tions.
With the complexity of modern urban areas, simulations for wind testing become a critical factor in urban design, helping to ensure stability and structural integrity for buildings, as well as comfort and safety for pedestrians. Assessing wind flow patterns, wind pressure calculations, and predicting phenomena like the Venturi effect or the wind effect on buildings are expensive processes. CFD wind analysis helps engineers investigate all of these factors early in the design process, before investing in wind tunnel testing.
With the drive towards developing sustainable building solutions, improving the energy efficiency and airtightness of new houses has become more important than ever. This has resulted in a mixed understanding of the most appropriate method to ventilate sustainable homes and, quite often, this causes homeowners to use ineffective or inadequate solutions
There are three methods that may be used to ventilate a building: natural, mechanical and hybrid (mixed-mode) ventilation.
The combination of modern airtight design and ongoing lifestyle changes underlines the need to understand the benefits of proper ventilation.
It is important to remember that 90% of the air we breathe comes from the indoor environ-ment due to the amount of time we spend in buildings at home or at work. There is also a growing reluctance to open windows due to the need to keep heat in during the colder months of the year, reduce noise and pollution and keep the home secure.
A lack of adequate ventilation causes problems to our homes by building up humidity, gases from furniture and furnishings, particles, biological compounds and radioactive gas. This can have a negative impact on the wellbeing of a home, so it is important to make sure our in-door environments have plenty of fresh air and are ventilated properly.
There are two general means of ventilation – natural and mechanical – and it is important to consider both methods before deciding on which process is the right solution for the project or home.
Natural ventilation Natural ventilation is best suited to dual aspect homes, the strategic po-sitioning of windows at high and low levels on the same façade will provide an adequate means of ventilating using the stack effect – the movement of air in and out of buildings.
Natural ventilation is easy to operate by opening and closing a window. However, there can be challenges in implementing a natural ventilation strategy. For example:
o Families spend most of their day out at work and school so the house is empty with win-dows closed for security reasons
o A lack of understanding of the way natural forces ventilate a building results in the wrong windows being opened at the wrong time
o Demands of family life make the opening and closing of windows low on the list of priori-ties
o The perception that windows cannot be opened in winter due to heat loss
o Slow reaction to operating windows by the occupants (the human factor) can result in overheating in the summer and excessive heat loss in the winter
Mechanical ventilation Mechanical ventilation is usually considered where a house has been designed for energy efficiency, such as a zero carbon home, which has exceptional air-tightness and where heat recovery (MVHR) is required.
Of course, the Building Regulations have always required some form of mechanical ventila-tion in kitchens, bathrooms and other areas with high humidity and odours using either inter-mittent extract fans or a balanced centralised system.
As with natural ventilation, there are challenges in implementing a full mechanical ventilation strategy. These include:
o Homeowners assuming that a running fan is costing money, leading them to switching it off
o Lack of maintenance and servicing over time reducing the quality of the air circulating the home
o Failure of components causing inadequate pre-heating of an MVHR system in the winter, leading to cold draughts
o Lack of understanding resulting in improper use of the system
o Poor installation causing the mechanical ventilation system to underperform and nega-tively impact the indoor environment
So which system, natural or mechanical, is best to use? There is no formula to determine which system is best to use when looking at a whole-year lifecycle analysis but there is plenty of scientific evidence and case study examples to show that natural ventilation is eas-ier to manage and cost-free.
However, there is also evidence to show that the use of mechanical ventilation with heat re-covery in the winter helps to heat the inside space and reduce the amount of energy re-quired for heating, thereby reducing the overall CO2 footprint. Of course, this is subject to the installation being carried out to the required standard.
It is generally recognised that future sustainable solutions may well benefit from a hybrid ventilation solution, where natural ventilation is used throughout the warmer months and me-chanical ventilation with heat recovery is used during colder months.
In addition, it is important that ventilation is adequately controlled for all seasons, which means households could overcome the human factor by automating specific windows in the home. This would ensure that a regular and timed ventilation strategy is in place regardless of lifestyle or family commitments, or indeed the time of year.
Key benefits of natural ventilation
• Reduced costs. As natural ventilation systems rely on natural forces, you’ll save significantly on your building’s energy consumption and therefore save significantly on your energy bills.
• Low maintenance. …
• Improved air quality. …
• Consistency. …
• Reduced carbon emissions.
Building ventilation has three basic elements:
• ventilation rate — the amount of outdoor air that is provided into the space, and the quality of the outdoor air
• airflow direction — the overall airflow direction in a building, which should be from clean zones to dirty zones
• air distribution or airflow pattern — the external air should be delivered to each part of the space in an efficient manner and the airborne pollutants generated in each part of the space should also be removed in an efficient manner.