Environment, Technology and Sustainability

Hocine Bougdah, Stephen Sharples

• Publisher: Taylor & Francis
• Year: 2009
• Print ISBN: 9780415403788
• eBook ISBN: 9781134140381
• Topic: Architecture
• Subtopic: Architecture General

This second volume in the Technologies of Architecture series – the only series of books tuned to the architectural technology syllabus – explores the environmental influences on building design.

Looking particularly at sustainable building, a holistic view is taken, so that the influence of any one set of choices on other areas – such as the trade-off of daylighting against thermal insulation, or the balance needed between heating and ventilation – are not overlooked. The authors discuss available technologies for establishing a suitable microclimate within buildings, for managing the transmission of sound and for minimizing the exploitation of scarce energy and of other resources.

Using the perspective of a designer who needs a sound scientific basis for arriving at the optimum outcome, this valuably informative volume is ideal for architectural technology students, as well as first and second year architecture students.

Part 1
Buildings and climate design

Chapter 1 PRINCIPLES OF CLIMATE DESIGN,

Introduction,

Basic elements of climate,

Climate classification,

Traditional climatic design,

Architectural design and climate change,

Chapter 2 SOLAR PRINCIPLES IN CLIMATIC DESIGN,

Introduction,

The sun and the Earth,

Solar geometry,

Solar time,

Solar analysis techniques,

Chapter 3 WIND FLOW AROUND BUILDINGS,

Introduction,

Nature of wind flow: the atmospheric boundary layer,

The generation of wind forces,

Wind flow and tall buildings,

Assessing wind flow problems,

Controlling wind flow problems from tall buildings,

Chapter 4 MICROCLIMATE, SITE PLANNING AND BIOCLIMATIC DESIGN,

Introduction,

Microclimate,

Optimising the microclimate of a site,

Bioclimatic design,

BIBLIOGRAPHY,

Chapter 1
Principles of climate design

Introduction

Winston Churchill said ‘We shape our buildings, and afterwards our buildings shape us’. The reverse is now probably true for climate – it has shaped human activity, and now human activity is shaping the climate. Historically, human activity and development have always been inextricably linked with climate. Many of the great ancient cities and civilisations developed in benign climates that were conducive to social, cultural and scientific development. Some civilisations, such as the Mayan, are also thought to have died out due to changes in their local climate. Figure 1.1 shows how a mean outdoor air temperature contour of 21°C linked the sites of many ancient cities.

One of the most basic human activities linked to climate is building to provide shelter from adverse external climatic conditions. Consequently, the study of the interactions between buildings and climate – building climatology – is as old as the concept of shelter itself. Early civilisations demonstrated a deep understanding of how built form could work with the prevailing climate to create habitable and comfortable internal environments. Caves were an early form of shelter which offered summer cooling and protection from wind, rain and snow. The Greek, Xenophon, in 400 BC, described the design and orientation of openings to provide natural heating and cooling in buildings. The Roman architect Vitruvius, in the first century BC, included in his famous Ten Books on Architecture advice on passive solar design and natural ventilation – indeed, the Romans passed sun-right laws to protect the solar access of existing buildings.

1.1

Although other factors (social, religious, cultural and economic) have been important, there is no doubt that climate has played a major role in shaping traditional vernacular architectural forms around the world. It was only in the early twentieth century that developments in structural design, materials technology and building services enabled tall buildings to be constructed of glass and steel with internal environments that could be decoupled from their external climate. A typical example of a climate insensitive structure, Mies van der Rohe’s Seagram Building in New York, is shown in Figure 1.2.

Such buildings tended to have high levels of energy consumption to maintain comfort. Concerns over fuel costs, environmental impact, sustainability and occupant health have led to a renewed interest in climate-sensitive building design. Many of the techniques that were intuitively learnt in the past are being re-visited and applied today in low energy, sustainable and environmentally-aware buildings. This section will consider some of the basic principles of climatic design and describe some of the ways in which a site’s microclimate can be used to improve the environmental performance of a building and the comfort of people located in and moving around the building. Climatic analysis techniques will be introduced and examples presented of some contemporary architectural responses to climatic design. The section is divided into three chapters. This chapter will describe how global climate types are categorised and consider how traditional architectural forms have responded to these climates. Chapter 2 will discuss some specific climatic elements (sun, wind, rain and snow) in terms of how they affect building design. Chapter 3 applied in terms of site planning and bioclimatic analysis and will conclude with some case study examples.

1.2

Basic elements of climate

Climate (from the Greek word klima meaning inclination) describes the long term atmospheric conditions observed at a site. Weather is the individual short term (hourly or daily) observations of climatic features. The major weather elements of interest in architecture are:

• Dry bulb air temperature (°C) – thermal comfort, heating and cooling
• Relative humidity (percentage) – thermal comfort, condensation, mould growth
• Precipitation (rain, hail, frost and snow) – drainage, loading, damage
• Wind speed and direction (m/s) – energy, ventilation, comfort, loading
• Sunshine hours – indication of solar availability
• Solar radiation (W/m²) – indication of solar energy options
  

In order to standardise weather measurements around the world similar procedures are followed in most countries. Air temperature and humidity are measured in a Stevenson Screen (Figure 1.3), which is a white, shaded and ventilated box raised 1.2m to 1.6m above the ground. Precipitation is collected in a ground buried container whose rim is just above ground level (to avoid collecting run-off water). Wind speed and direction often use a cup anemometer and vane placed on a mast 10 metres above open ground or at an effective height of 10 metres above surrounding buildings. A wind rose shows the annual frequency and distribution of wind speeds and directions. Sunshine hours are measured using a solid glass sphere called a Campbell Stokes Sunshine Recorder. The sphere is typically 100mm in diameter and focuses sunlight on to a wax chart that scorches to show the daily duration of the sunlight. In the USA the Marvin Sunshine Recorder is more commonly used. Solar radiation measurements are made using a solarimeter, which consists of a blackened thermopile housed under a protective glass dome. As the thermopile absorbs the solar radiation its temperature increases and an electrical signal proportional to the heating effect is recorded.

Representative climate data for many locations can be freely found on websites such as those given in the webliography on pp. 47–48 (www.weatherbase.com and www.climate-zone.com) at the end of the section. Commercial climatic software, such as Meteonorm, provides an enormous database of weather information as well as the possibility of creating weather files for sites where no weather records have been kept.

1.3

Climate classification

World climates, as studied by meteorologists, display a wide range of complex characteristics and variations. For building design purposes it is possible to make use of a simplified version of the climate classification system initially developed by Köppen in the early 1900s. This simplification divides the world’s climates into four basic types: polar/cold, temperate, hot dry and hot humid. Figure 1.4 shows these climate zones.

Polar / cold climates

This type of climate is typically found at high latitudes above 55°. The key shelter problem in polar / cold climates is providing thermal comfort against the extreme cold. Average minimum air temperatures in winter may be below −15°C, with the lowest temperatures dropping below −40°C. In the summer temperatures will not rise above 10°C. The coldest temperature ever recorded was −88°C at Vostock in Antarctic. Strong winds can add to the chill factor. Perhaps surprisingly, polar regions are dry, and may have similar levels of precipitation to those found in desert areas.

1.4

Temperate climates

This type of climate is usually found at latitudes between 30° and 55°. The main shelter issue with temperate climates is coping with the seasonal variations. This leads to potential overheating problems in summer but overcooling issues in winter. In the summer air temperatures may average 25°C but then drop down to as low as −115°C in winter. Humidity levels are not normally a problem. Precipitation may occur at any time of the year.

Hot dry climates

This type of climate is usually found at latitudes between 20° and 35°. The main shelter issue is overheating. Mean summer temperatures are around 25°C but can reach a maximum of 45°C. Clear nocturnal skies can cool temperatures down as low as −10°C. The hottest temperature ever recorded was 58°C in Libya in 1922. Relative humidity is low and precipitation is very low. This lack of moisture, together with strong seasonal winds, can make wind-borne sand storms a major problem.

Hot humid climates

This type of climate is usually found at latitudes between 0° and 25°. The main shelter problems are overheating and oppressively high humidities. Day time temperatures do not normally exceed 35°C, but night time temperatures will often not drop below 20°C. Relative humidities are very high, reaching 80 per cent in some months. Rainfall is frequent and occurs as heavy falls, typically in short, intense spells. There is little seasonal variation in the climate, apart from rainy seasons such as monsoons. A comparison of the four climate types is given in Figure 1.5

Traditional cli...

Table of contents

• Cover Page
• Title Page
• Copyright Page
• Introduction
• PART 1 BUILDINGS AND CLIMATE DESIGN
• PART 2 BUILDINGS AND LOW ENERGY DESIGN
• PART 3 ENERGY SYSTEMS AND SERVICES IN BUILDINGS
• PART 4 BUILDINGS AND LIGHTING DESIGN
• PART 5 ACOUSTIC DESIGN AND THE AURAL ENVIRONMENT
• PART 6 SUSTAINABLE BUILDING DESIGN
• PART 7 CASE STUDIES