Commercial buildings are not the bad guys. We need them all the time. They provide a sizeable proportion of our urban needs and services, but commercial buildings typically consume a large chunk of urban power. Studies in America have shown that the power consumed in commercial buildings account for up to 30 per cent of the total electricity consumed annually.* Reducing power consumption in commercial buildings is one of the prime objectives of green architecture, and in the last several years, various approaches have been formulated on how to achieve this. One of the more basic means to do so is to plan a building’s orientation to optimise heat gain in relation to the sun’s path and consider wind direction, thus reducing the heating/cooling load on power consumption, increasing the efficiency of building services. With the right HVAC mechanical engineering consultants and electrical design services working on an intelligently oriented building, a significantly effective energy-efficient building design can be formulated.
When we talk about commercial buildings, we refer to office buildings, hotels, hospitals, shopping malls or other buildings used for retail. In general, these buildings are multistoried and use power continuously throughout the day and sometimes through the night, contributing to greater power consumption.
Typically, commercial buildings are oriented to make the best use of street appeal, view scenic surroundings or for drainage considerations, but skyrocketing energy costs mean that designers and builders must attempt to incorporate the benefits of free solar energy into building design, with the result of reducing carbon footprints and increasing the building’s marketing value. At the same time, occupants experience the same, expected indoor comfort with reduced energy bills.
The orientation of a building affects the heating, cooling, lighting, daylight access, ventilation and views of occupants. Variations in the usage of power is determined by solar gains impacting cooling and the effect of daylight affecting the use of artificial lighting. Considering climate, low-E coatings on glazing can regulate solar heat gain. Cold climates may need passive solar gain, while hot climates may need a reduction in solar gain.
Orientation towards certain directions is advantageous during some climates. In cold climates, buildings-oriented west of north will result in increased solar gains in the afternoon, and buildings-oriented east of north will be warm during the mornings. At locations with warm climates, buildings-oriented east of north will be better positioned to capture cooling breezes. In commercial buildings, therefore, it must be determined early in the design stage when more warmth would be beneficial, depending on occupancy rates.
For commercial buildings in the Northern Hemisphere, orientation towards the sun requires the largest side of the building to face south and have the most windows, as the sun rests longer on a building’s southern walls. When windows face east or west, they allow the entry of excessive heat, making air conditioners work long and hard during the summer. They also cause issues with glare in commercial buildings. During winters, maximum exposure to daylight provides passive heat, reducing HVAC system dependency.
It’s easy to see that building orientation is ideally based on the geographical location of the building and the local climate for most of the year.
Orientation for Passive Cooling
When commercial buildings are oriented well and decisions are taken to incorporate landscape design and shading elements, passive cooling can be achieved fairly simply. Proper orientation can exclude bright, hot sun and hot winds while accessing cool breezes in certain climates. Hot, humid climates should ideally have buildings that are protected from direct sunlight and heat from nearby buildings (radiant heat). This can be achieved if landscape and adjacent buildings funnel beneficial breezes and shading is provided to all or most external walls.
How the sun travels, or its solar path, influences a building’s heat gain to a large extent. Intelligent building orientation can be crucial in passive solar construction. According to research, a ridgeline running east-west on a rectangular building is ideal. This will maximise the length of the southern side of the building, and several windows on the south will help. Due to the intensity of the summer sun, the northern side of the building ideally should have fewer windows. Of course, directions should be considered as a solar reference and not magnetic north, which varies considerably.
So, what really happens on the sun’s path?
The Truth about the Sun’s Path
Every child will tell you that the sun rises in the east and sets in the west. If we want to be strictly accurate, this happens only on 2 days of the year, the autumnal and vernal equinoxes. During the rest of the year, things are slightly different. The Earth’s tilt on its axis means that the sun rises and sets slightly south of east and slightly south of west during the winter, and slightly north of east and slightly north of west during the summer. The angle is slight and depends on the season and how far the observer is from the equator.
What this means is that the winter sun lives in the southern sky and the summer sun lives in the northern sky, in general. For those living in the Southern Hemisphere, these directions are reversed, which means that for those in Oceania, most of South America, almost half of Africa and some parts of Asia, the winter sun rises in the northeast and sets in the northwest, and the summer sun rises in the southeast and sets in the southwest.
Confusing? Not really. Building engineering designers and architects need to consider these directions, locations and seasons for best results.
Having a south-facing orientation results in shading from the summer sun, reducing solar gain but still accessing sufficient daylight to reduce energy loads associated with artificial lighting. Summer sun angles are high, while winter sun angles are low, enabling the easy entry of light and heat to a building. When buildings are oriented to the north as well, they receive sufficient amounts of indirect daylight, and solar gain, direct light and direct glare are reduced. These factors are more difficult to control if building facades face east or west, as they will then deal with the full intensity of the rising or setting sun, respectively.
In addition to the solar path, building orientation can also harness wind movement for optimum results, even having the potential to utilise wind turbines to generate power. Also, winds and wind patterns can help regulate heat gain. Prevailing winds in a geographical area are winds that blow predominantly from a certain general direction over that location. Studying, analysing and calculating wind data for certain locations can help design commercial buildings that can use summer breezes for passive cooling or protect the interiors from strong wintry winds. These calculations can even possibly prevent the pile-up of snow outside entrances.
In general, chilling winter winds originate in the north and the west. For coastal areas, breezes typically originate from onshore directions, and cold breezes blow down from the mountains to the valleys. Insulated glazing on the building’s sides can limit the effects of these winds.
What happens when builders are unable to choose building orientation?
Building orientation must be fixed on certain plots, especially if they are commercial buildings. The orientation cannot be chosen or planned. If the climate is hot and does not require heating, the site can be developed so that surrounding buildings and trees shade the walls and can channel cool breezes inside.
Excluding photovoltaic collectors and areas deliberately exposed for solar power generation, roofs can be shaded as much as possible. Windows facing east and west should be minimised or eliminated, and those that can’t be avoided should be well shaded. Unwanted heat enters through unprotected glass, so shading the glass can reduce heat gain.
Tips to Regulate Heat Gain through Orientation
Sometimes, builders can use these simple tips to regulate heat gain, depending on the climate:
Though street appeal and lot dimensions may ultimately limit a building’s orientation to benefit from passive solar approaches, innovative designs by HVAC mechanical engineering consultants and efficient electrical design services can result in operational energy reduction. Commercial buildings will use less energy for heating and cooling, curbing power consumption, if they are properly oriented according to their geographical location and climate. This will then result in lower power costs without compromising indoor comfort.
When we talk about commercial buildings, we refer to office buildings, hotels, hospitals, shopping malls or other buildings used for retail. In general, these buildings are multistoried and use power continuously throughout the day and sometimes through the night, contributing to greater power consumption.
Typically, commercial buildings are oriented to make the best use of street appeal, view scenic surroundings or for drainage considerations, but skyrocketing energy costs mean that designers and builders must attempt to incorporate the benefits of free solar energy into building design, with the result of reducing carbon footprints and increasing the building’s marketing value. At the same time, occupants experience the same, expected indoor comfort with reduced energy bills.
The orientation of a building affects the heating, cooling, lighting, daylight access, ventilation and views of occupants. Variations in the usage of power is determined by solar gains impacting cooling and the effect of daylight affecting the use of artificial lighting. Considering climate, low-E coatings on glazing can regulate solar heat gain. Cold climates may need passive solar gain, while hot climates may need a reduction in solar gain.
Orientation towards certain directions is advantageous during some climates. In cold climates, buildings-oriented west of north will result in increased solar gains in the afternoon, and buildings-oriented east of north will be warm during the mornings. At locations with warm climates, buildings-oriented east of north will be better positioned to capture cooling breezes. In commercial buildings, therefore, it must be determined early in the design stage when more warmth would be beneficial, depending on occupancy rates.
For commercial buildings in the Northern Hemisphere, orientation towards the sun requires the largest side of the building to face south and have the most windows, as the sun rests longer on a building’s southern walls. When windows face east or west, they allow the entry of excessive heat, making air conditioners work long and hard during the summer. They also cause issues with glare in commercial buildings. During winters, maximum exposure to daylight provides passive heat, reducing HVAC system dependency.
It’s easy to see that building orientation is ideally based on the geographical location of the building and the local climate for most of the year.
Orientation for Passive Cooling
When commercial buildings are oriented well and decisions are taken to incorporate landscape design and shading elements, passive cooling can be achieved fairly simply. Proper orientation can exclude bright, hot sun and hot winds while accessing cool breezes in certain climates. Hot, humid climates should ideally have buildings that are protected from direct sunlight and heat from nearby buildings (radiant heat). This can be achieved if landscape and adjacent buildings funnel beneficial breezes and shading is provided to all or most external walls.
How the sun travels, or its solar path, influences a building’s heat gain to a large extent. Intelligent building orientation can be crucial in passive solar construction. According to research, a ridgeline running east-west on a rectangular building is ideal. This will maximise the length of the southern side of the building, and several windows on the south will help. Due to the intensity of the summer sun, the northern side of the building ideally should have fewer windows. Of course, directions should be considered as a solar reference and not magnetic north, which varies considerably.
So, what really happens on the sun’s path?
The Truth about the Sun’s Path
Every child will tell you that the sun rises in the east and sets in the west. If we want to be strictly accurate, this happens only on 2 days of the year, the autumnal and vernal equinoxes. During the rest of the year, things are slightly different. The Earth’s tilt on its axis means that the sun rises and sets slightly south of east and slightly south of west during the winter, and slightly north of east and slightly north of west during the summer. The angle is slight and depends on the season and how far the observer is from the equator.
What this means is that the winter sun lives in the southern sky and the summer sun lives in the northern sky, in general. For those living in the Southern Hemisphere, these directions are reversed, which means that for those in Oceania, most of South America, almost half of Africa and some parts of Asia, the winter sun rises in the northeast and sets in the northwest, and the summer sun rises in the southeast and sets in the southwest.
Confusing? Not really. Building engineering designers and architects need to consider these directions, locations and seasons for best results.
Having a south-facing orientation results in shading from the summer sun, reducing solar gain but still accessing sufficient daylight to reduce energy loads associated with artificial lighting. Summer sun angles are high, while winter sun angles are low, enabling the easy entry of light and heat to a building. When buildings are oriented to the north as well, they receive sufficient amounts of indirect daylight, and solar gain, direct light and direct glare are reduced. These factors are more difficult to control if building facades face east or west, as they will then deal with the full intensity of the rising or setting sun, respectively.
In addition to the solar path, building orientation can also harness wind movement for optimum results, even having the potential to utilise wind turbines to generate power. Also, winds and wind patterns can help regulate heat gain. Prevailing winds in a geographical area are winds that blow predominantly from a certain general direction over that location. Studying, analysing and calculating wind data for certain locations can help design commercial buildings that can use summer breezes for passive cooling or protect the interiors from strong wintry winds. These calculations can even possibly prevent the pile-up of snow outside entrances.
In general, chilling winter winds originate in the north and the west. For coastal areas, breezes typically originate from onshore directions, and cold breezes blow down from the mountains to the valleys. Insulated glazing on the building’s sides can limit the effects of these winds.
What happens when builders are unable to choose building orientation?
Building orientation must be fixed on certain plots, especially if they are commercial buildings. The orientation cannot be chosen or planned. If the climate is hot and does not require heating, the site can be developed so that surrounding buildings and trees shade the walls and can channel cool breezes inside.
Excluding photovoltaic collectors and areas deliberately exposed for solar power generation, roofs can be shaded as much as possible. Windows facing east and west should be minimised or eliminated, and those that can’t be avoided should be well shaded. Unwanted heat enters through unprotected glass, so shading the glass can reduce heat gain.
Tips to Regulate Heat Gain through Orientation
Sometimes, builders can use these simple tips to regulate heat gain, depending on the climate:
- Solar-oriented floor plan – Individual floor plans in multi-storey buildings can face the sun for maximum heat gain.
- Tall trees for shade – Evergreen trees on the north side of the building will provide shade during the summer. However, trees can pose certain dangers, so builders must consider age, species, growth rate and canopy cover before deciding to plant new or retain existing trees on the building lot.
- Sufficient number of windows – Too many windows can drain heat from the interior during the winter, and they can allow the entry of more heat to the interiors during the summer.
- Angled glass – It’s not always necessary to have vertical glass. When glass is sloped to match the sun’s angle, reflection can be minimized. Insulation effects are reduced with angled glass, but possible solar gains need to be balanced with heat loss to the outdoors.
Though street appeal and lot dimensions may ultimately limit a building’s orientation to benefit from passive solar approaches, innovative designs by HVAC mechanical engineering consultants and efficient electrical design services can result in operational energy reduction. Commercial buildings will use less energy for heating and cooling, curbing power consumption, if they are properly oriented according to their geographical location and climate. This will then result in lower power costs without compromising indoor comfort.
