As much as we love air conditioning systems, we can’t pretend they are not a just little unsightly. Hence, I thought an article on ‘How to hide air conditioning units’ would be a worthy addition to our air conditioning blog. This article looks at some of our favourite ideas for disguising or hiding your outdoor air conditioning unit.

In the UK, home air conditioning is becoming increasingly popular as our summers seem to be getting warmer. Many modern houses now rely on air conditioning systems entirely for heating, as well as cooling. As much as this is a energy efficient and very much the future, it brings with it the need to hide an outdoor air conditioning unit.

Often we can hide units down side walls or alley ways where they are not seen, but equally often there is no choice but for them to be on the back or front of your house.

Below are some ideas on how to hide the dreaded outdoor AC unit. Some of them are well crafted things of beauty, but others are very DIY and can be knocked up with odd bits of timber or wooden pallets. If you are not up to making your own air conditioning screen, then Google ‘wheelie bin screens’ and there are lots of off the shelf solutions which are quick and easy to install.

Basements represent a unique challenge when it comes to air conditioning and ventilation, particularly the latter. They can be further complicated if these areas are to have high student occupancy rates.

This was the challenge we faced on a recent project at a college in Oxford. Their unused basement was to be converted into three new classrooms and a student breakout area. The total occupancy was for 80 students at any one time. Initially we were ask to cost a proposal designed by a professional M&E consultant. The cost of this was such that the whole project became unviable. It was at this point Air Intelligence offered to design a solution more fitting with the budget available.

The Challenges:

Volume of ventilation: The whole nature of classrooms is that they have high occupancy rates for the size of the space. The basic requirement for classroom spaces is for the ventilation to provide 8 litres of fresh for each person, every second of the day. This means a classroom of 20 people needs 576 m3/hr of fresh air. Across all four new rooms, this was over 2300m3/hr.

Ducting Routes: The second complication in ventilating a basement is finding a route through which ductwork can be installed. Since the ventilation unit would be roof mounted, we needed to find a route from here to where the air is needed. Fortunately, we were able to adapt and enlarge an existing riser cupboard.

Ventilation capacity: Next up was finding a ventilation unit that was powerful enough to provide the required air flow, but small enough to fit in the small roof space we had available. This is where Barkell, based in Co. Durham stepped in. Their Therm-x range of air handling units come in a range of sizes and configurations. Compared to the alternatives, it was the only system that could provide the duty, but be small enough to fit the available space. At 500kg, it required a telehandler type forklift to get it onto the ground floor roof, but after that, it was relatively easy to install.

Fire Safety Regulations: Being a basement, meeting fire and smoke safety regulations was our next challenge. We had to ensure the system:

1.  was linked to the fire alarm such that it would automatically shut down in the event of a fire. Its very important ventilation systems do not feed fires with fresh air.
2. Smoke sensors in the ductwork that linked to the fire alarm that ensured the ventilation system automatically shuts down in the event of a fire inside the air handling unit.
3. The air handling unit can be made to operate in ‘exhaust only’ mode to draw out smoke from the basement after a fire.
4. Fire and smoke dampers between spaces to prevent transfer of smoke/fire.

Limited ceiling height: The next challenge was finding air conditioning units that could fit above the very limited space above the new suspended ceiling. In the end, we went for Panasonic 10kW PACi ducted units. This are only 250mm high, which is probably to lowest currently on the market. Not only that, they also can have a pipe run of up to 50m.

Schools represent much higher occupation levels than a typical commercial office building, hence the bioburden becomes even greater. What is bioburden?….It is the number of non-sterilised living bacteria in a space.

The bacteria particulates can be brought in on people’s clothing, through open doors and windows. The activity level of most young people increases the shedding of skin cells and other particulates which makes school air some of the dirtiest air in any environment. This makes air quality in schools even more important than most other types of buildings.

For any parent who has taken their child to school first thing in the morning and collect them in the afternoon, the difference in the smell of the school at the end of the day is astonishing. For those in the school, they have become accustomed to the odour and do not realise their air is full of particulates and odours. In addition, cold, dry air is a common asthma trigger and can cause children to have flare-ups. Hot, humid air also can be a problem. 

STEP 1: Air Conditioning

Air conditioning in schools is the first major step in improving air quality. These systems can both heat and cool the air, most importantly they contain filters that remove bacteria and other particulates. Typical wall mounted air conditioning units in a classroom can filter the air 20 times every hour (this is cleaning the air in the entire classroom, every 3 minutes) , which prevents particulates from being transmitted around the classroom from one person to another.

Not only does Air Conditioning mean students and teachers can work more efficiently in a classroom with a comfortable temperature, it shall reduce transmission of ailments and ultimately absenteeism. 

STEP 2: Ventilation

As we have discussed, installing Air Conditioning in a classroom is the first major step to improve air quality. The second step to further improve air quality is the introduction of new fresh air into the classroom.

In 2018, the government’s Education & Skills Funding Agency released Building Bulletin  101 (Guidelines on ventilation thermal comfort and indoor air quality in schools). This comprehensive document shows Regulations and Guidance on ventilation, thermal comfort and indoor air quality to the internal environment in schools. Although this document is a benchmark for schools, the reality is the limited school budgets often results in this rarely being achieved other than in new or refurbishment projects.

Just because it may prove difficult for schools to meet this benchmark, it does not mean they are unable to realise many of the benefits of improved ventilation. At Air Intelligence, we are experienced at delivering low cost fresh air ventilation solutions into classroom environments. Typically these are ‘heat recovery’ ventilation systems that both supply fresh air (1) and extract stale air (2) at the same time. To be energy efficient, they use a heat exchanger (3) to absorb the heat from the extracted air and apply this to the new fresh air.

Getting aesthetically pleasing air conditioning and ventilation to shops and restaurants and shops has always been slightly challenging.

Visible ducting used in a restaurant.

This is now changing with innovations in ducting fabrication is now allowing new ways of delivering air conditioning and ventilation to shops and restaurants, helped by the increasing trend for more industrialised and rustic feel to the overall interior design.

Visible ducting used in a retail space.

Instead of trying to hide air conditioning and ducting equipment, interior designers are making a feature of it. Some are even using the ducting to mount lighting. Some types of ducting can also be painted to blend in with the ceiling or to stand out as an architectural feature. 

Visible Oval Ducting

Where design constraints and space limitations demand, such as in ceilings, floor voids and walls, then flat oval duct offers significant advantages.  It also boasts fewer supports and site joints than the rectangular ductwork. The air tight structure ensures less air leakages, improved flow of air, and reduced noise which makes it ideal for use indoors and it’s is also watertight

Oval Ducting

On the 5th June 2017, a news article was published on the BBC website…

How air conditioning changed the world

The article by Tim Harford discussed how instrumental the invention of air conditioning has been to the modern economy. The full article is HERE, but the main points are as follows:

• Early printing presses had huge problems with humidity. To solve the problem a young engineer called Willis Carrier figured out that circulating air over coils that were chilled by compressed ammonia maintained the humidity at a constant 55%. The incidental side effect of this was invention of cooling of the air.
• The growth of shopping malls and theatres has only been enabled because of our ability to cool enclosed spaces.
• Early computer development was only achieve because of our ability to cool the massive temperatures generates by computers. Air conditioning remains a key feature of all large scale computer rooms.
• Air conditioning changed the way we build our buildings. The glass fronted high rise buildings that dominate our large cites could not exist without air conditioning.
• It also changed our demographics. Its hard to imagine the rise of cities like Dubia or Singapore without air conditioning.
• Air conditioning is also responsible for lower mortality rates during heat waves.
• It has made us more productive in offices and improved leaning in schools.

With a fast growing market for VRF heat recovery air conditioning technology, the ability to grow operational efficiencies is becoming more of a realisation than simply a design potential.

A typical VRF heat pump system can remove energy from one space and reject it to another, for example when cooling. The energy would be taken away from the indoor space and rejected outside, with all indoor units of only having the option of operating in the same mode – whether that be heating or cooling.

A heat recovery VRF system provides connected indoor units operating in heating and cooling. Energy removed from a room being cooled can be used to heat other rooms, therefore achieving an energy balance. This could potentially reduce energy consumption by 30%

It is also possible to transfer heat to water via equipment such as LG’s Hydrokits. With a system – connection capability matching fan coils, Hydrokits can achieve water temperature of up to 80degrees, have a potential heating capacity of 30kW from a single unit  as well as producing cold water down to 6 degrees.

The real system efficiency gain is being operational when other connected items are operating in an opposite mode. It is now common practice for a commercial VRF specification to include some method of Hydrokit application, whether to provide domestic hot water or hydronic heat exchangers inside ductwork.

When designing VRF projects, care should be taken to maximise efficiency gains, taking into consideration water flow rates, water temperatures, and the method of emitters being used.

Whilst most people use a low – loss header or thermal store with a supply of water at a single temperature to provide multiple emitters requiring different temperatures, a variation in leaving water temperature from a Hydrokit will have an effect on how efficiently it is performing.

The Hydrokit has the potential to provide two flow/return water temperatures and output signals to valves to divert the flow. There can be a lower setpoint for underfloor heating and a higher setpoint for portable  hot water, which maximises efficiency gains and serving each area as required.

The Hydrokit can regulate its water temperature between points selected at commissioning, enabling heat emitters to avoid overshooting temperature in a design space.   

It is selected on capacity and maximum leaving water temperature for the entire load, so efficiency is not maximised. It is usually found that approximately 80% is for space and heating and about 20% is for portable hot water.  In most cases, the designation of 100kW of high temperature Hydrokits to reach the temperature required for domestic hot water is unnecessary and increases the capital cost for the project and reduces the potential operating efficiency.

Most of the load would be met using R410A to heat water, with the extra temperature required for domestic hot water being achieved using cascade R134a transfer.

Whilst the development of new technologies is important to maximising energy saving methods, we must fully understand their full potential in terms of application at the initial design stages in order to deliver consistently high efficiencies.

The Air Conditioning Equipment

Fine Tuning Ducted VRV Air Conditioning