Friday, 01 July 2016 00:00

Specifying the right HVAC system for your project

    Whether you’re newly qualified or a highly experienced designer, choosing a new HVAC system on behalf of a client is probably one of the most daunting tasks, be it for a new build or a refurbishment, a single dwelling or a multi-unit development (MDU). Here, Simon Buddle, Senior HVAC Consultant at Cornflake and Education Director at CEDIA, offers his hot tips and cool advice for specifying HVAC systems for your clients.

    A typical HVAC system is a sophisticated grouping of technologies that establishes an environment in which your client, and their family, will live for a large portion of each day. And, as they will be living with the equipment for a long time, it’s a good idea to research all the options before making any recommendations.

    Before you start

    Make sure you have access to quality information. Websites for independent trade bodies such as HEVAC, FETA, CEDIA and BIID are good starting points. Employ a reliable and knowledgeable contractor. Get an energy audit, which is useful if you are replacing an existing system, most utility companies offer audits to help identify ways to save energy.

    Know the basics

    Measure each room and know the volume of all spaces and each floor of the house. Engineers start with volumes to establish the ‘load’, or how much power a system will need. Engineers also factor in door and window spaces, ceiling heights, insulation, climate data and other abstract factors.

    Collaboration is key

    Choose an integrator you can depend on for professional expertise, you’ll be working closely, so a healthy working relationship is essential. You should also check references and credentials with trade associations and interior design bodies. Another tip is to consult with a few contractors to determine the system specifics, then seek bids on what you consider will be the essentials for the project. Lastly, choose a contractor who listens and answers your questions most satisfactorily.

    Advice for a single unit dwelling

    The top two priorities are comfort – constant, correct temperature – and great air quality. Your goal is to achieve the optimum combination of three systems: heating, cooling and MVHR.

    Heating

    Underfloor heating is typically most efficient as it heats the building’s infrastructure. The floor, walls and timbers are all warmed through and then slowly release heat. Initially, the building can take a while to warm up, but once it’s at the desired temperature it can be set to a preferred level, so its highly energy-efficient. Plus, of course, nothing is visible so underfloor heating scores well aesthetically with discerning clients and interior designers.

    Historically, radiators were set against an outside wall or under a window, where cold air drops to the floor. With the logic being that older properties are poorly insulated with single glazing and are prone to draughts. So, if a radiator was positioned opposite a window this would cause cold air to be drawn across the floor due to the convection process. Now with properties far better insulated and double glazing the norm, plus radiators available in a wealth of shapes and sizes that can be positioned to best suit the room, radiant heating has a renewed appeal to homeowners. A word of caution: overspecifying radiant heat is easy – sticking in large radiators may seem like a good idea, but is rarely a success as radiators simply can’t throw heat far enough.

    Cooling

    There are literally thousands of air cooling systems on the market. I recommend seeking kits that sit within ceiling voids. This obviously requires extra ductwork and an extractor on the outside of the building, but it looks much smarter. ‘Seamless and hidden’ is very popular at the top-end of the residential market in high-spec homes, where air conditioning kits are hidden in dining rooms, media dens, home cinemas and entertaining rooms.

    MVHR

    MVHR is clever technology which is predominantly installed in bathrooms and kitchens to provide clean air. A fan constantly runs on a ‘trickle’ setting, drawing air through at a low rate and is automatically boosted when the lights are switched on. International clients particularly like MVHR, but must appreciate there are strict UK wiring rules and regulations, for instance the fan has to run for several minutes after the light has been turned off.

    A top tip for controlling MVHR is to connect it to a Building Management System (BMS) which can overrule manufacturers’ settings and turn it off when the occupants are away to save energy. It’s also worth bearing in mind some people don’t like MVHR’s constant low throb, especially at night time. A good BMS can override the device and allow the occupant to make their own usage choices.

    Behind the scenes, engineers take great pride carefully integrating HVAC systems into a building’s infrastructure, often with spectacular colour-coordinated wiring and super neat control racks that aid future servicing, but designers and clients, quite rightly, seek to hide all visible elements. Discrete, stylish touch pads, such as Deseo, are growing increasingly popular; combining the system thermostat with other intelligent functions in one single, neat room panel.

    Advice for multiple development units

    Heating

    Traditionally, developers have installed a heating system and boiler in each unit, but that’s no longer necessary. Consider instead, a shared hot water system for the development, it’s a highly cost-efficient option and, importantly, will also free up valuable floor space and reduce metal works.

    Cooling

    An air conditioning unit in each property can now be engineered to run off one large, shared condenser, offering huge cost and energy-savings. Savvy designers score brownie points with this clever recommendation as it has an immediate cost-saving effect on a client’s procurement budget.

    MVHR

    Ventilation is still largely specified on a one by one apartment basis, but can be streamlined if engineers and the design team agree on a few simple compromises. Designers naturally want the smallest possible grilles and discreet baffles, whereas the M&E team want maximum airflow based on their calculations, and therein lies the rub. Smaller vents reduce the figures and the effectiveness of the system, so engineers have to pump the air harder which can result in an annoying rattle. It’s a perennial problem which designers tend to ‘win’ as they have the client’s ear, but really it’s a futile battle, and could come back to haunt the team.

    Ventilation issues are always solvable, requiring both sides to apply common sense to provide the best outcome for the client. Style over substance is never going to be a practical solution. Designers and HVAC installers must work closely together to balance design with functionality and provide a fitting and practical solution for the property. Communication and collaboration are definitely key when it comes to great HVAC installations.

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