Heat Efficiency Of Modular Homes

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A modular home is heat-efficient when the heating or cooling demands are significantly reduced, cutting down the energy consumption. Heat efficiency is a characteristic that isn’t necessarily linked to modular home construction but that can be easily achieved with this building method given the mechanization of the construction process. Still, in order to obtain a heat-efficient modular home, it should be designed with this intention in mind and balancing all the necessary strategies in a smart design.

Designs strategies to achieve an energy-efficient modular home:

Passive design strategies
Active design strategies.

Heat-efficient modular homes are more commonly recognized as energy-efficient homes and are becoming more and more popular in recent years. This popularity is a result of the indisputable need for a more sustainable construction, though some added benefits such as lower utility bills may have greatly contributed to this increased demand.

Passive strategies to design a heat-efficient modular home

To ensure a heat-efficient home, the most important elements we must consider are integrated into the house design. A smartly designed home is orientated and built with the intention of reducing the need for artificial energy consumption, also known as active design strategies. Passive strategies take into account the climate and natural elements present on the site to ensure their interaction helps achieve an ideal temperature indoors [1] which should remain between 20 to 26ºC (68 – 79ºF) [2].

Orientation of the house

The very first parameter to consider when designing a heat-efficient modular home is the orientation of the house according to its climate and location. If temperatures outdoors are very hot all year long the goal is to avoid heating the indoor air. Therefore, the house should be orientated and designed to reduce sun exposure as much as possible. In this situation, a location that receives a heavy shade or a site with plenty of trees would be ideal. Also, integrated design strategies such as canopies, pergolas or shutters; are a great tool to protect the home from the sun rays and heat when the temperatures rise.

Modular homes placed in cold climates should follow the opposite strategies since they will need to receive as much sun as possible to naturally heat the indoor air. Therefore, the ideal building site in these circumstances will have unobstructed sun and be sheltered from the wind to maintain the temperature indoors as warm as possible. Also, when deciding the orientation of the main facades of the building we will choose those directions receiving the most amount of sun.

Insulation and Windows

Insulation and air-tightness are two key elements to consider when designing a heat-efficient home. Every modular home built today is quite well insulated, even those homes that are not classified as energy or heat-efficient are built up to building code standards and heat loss is taken into consideration to a certain degree, in these regulations [3]. However, the building code requirements are insufficient to acquire the qualification of heat efficiency.

The insulation and air-tightness of a heat-efficient modular home are carefully designed: choosing windows with the Energy Start certificate or NFRC labels [4] and taking special care in areas like the joint between the wall and the window to avoid heat loss. Some modular home companies such as Dvele Homes, design their houses to match Passive house standards [5], managing to reduce the energy consumption up to 65% to 75% less energy than a standard home [6].

Building Materials and Thermal Mass

The building materials chosen to construct the house have a direct impact on the heat-efficiency values of the modular home. One of the most valued characteristics of a material in this context is thermal mass, which is the ability of a material to absorb, store and release heat [1]. A good example of a popular construction material with high thermal mass is concrete.

During the day, the sun rays will hit the concrete wall and since it has thermal mass, it will absorb this heat and store it within itself. At night as temperatures drop, the concrete wall will release and disperse this heat in the area around it. Thermal mass is as good as thermal insulation and in some climates, insulation and thermal mass could be exchangeable even if they work in a different way. Like insulation, thermal mass allows the building to regulate its indoor temperature naturally reducing the requirements for a heating and cooling system.

Active design strategies to improve energy-efficiency

While active strategies won’t help reduce the need for heating or cooling systems, they are very important elements to consider to ensure the energy required in the house remain minimal. Any energy-efficient home will try to reduce as much as possible the need for active strategies, though when needed, we shall choose devices that are designed to save more energy such as those rated with the Energy Star [7].

Heating and Cooling Systems

All passive strategies are conceived to avoid or reduce the need for heating and cooling systems. However, most energy-efficient modular homes will still require some heating or cooling to maintain an optimal indoor temperature. In these cases, choosing a system with optimal performance is key.

Modular home manufacturers who have experience designing heat-efficient and energy-efficient homes pay close attention to these systems. Method Homes, for example, a company that builds homes up to Net-Zero energy-efficiency requirements, uses highly efficient heating and cooling systems that are 250% to 300% more efficient than the standard ones [8].

The importance of ventilation and Heat Recovery

As seen with passive strategies, avoiding heat loss is key to maintaining a good indoor temperature naturally. However, to maintain a healthy indoor air, ventilating is key. Ventilation is the process of replacing the “dirty” indoor air with fresh air and it is usually done by manually opening the windows. However, it is common nowadays to integrate mechanical ventilation systems.

Especially in those climates where temperatures get really cold, it is important to supply the modular home with mechanical ventilation. Since in these situations, the indoor temperatures are highly different from the outdoor temperatures it is easy to lose heat with natural ventilation or even a ventilation system. To avoid this issue, it is recommended to install a heat recovery system to avoid temperature losses and reduce the need for an extra heating supply [9].

Alternative energy solutions

It is common for heat and energy-efficient homes to include energy production systems such as solar panels or geothermal energy exchangers. When these systems are used together with all the other strategies, it is possible to achieve Net-Zero standards making as much energy on-site as it will be consumed over the course of one year [10]. Some modular home companies such as Plant Prefab, are already setting themselves ahead in designing every one of their homes to meet Net-Zero standards [11].

In the U.S. the most common source of residential renewable energy is Solar Power. Though, depending on the situation some properties opt for other systems such as wind energy, micro hydro-power or hybrid systems combining solar and wind [12]. Most of the modular home companies offering energy-efficient homes offer photovoltaic solar installation. While generally installing Solar panels has an additional cost, it is an investment that usually pays back in around 8 years [13].

The benefits of a heat-efficient modular home

Choosing a heat-efficient modular home usually represents an increased construction cost, though it should be considered a long-term investment since it definitely reduces the utility bill cost enormously. Moreover, the energy cost isn’t the only benefit of a heat or energy-efficient modular home.

Lower energy bills: Heat-efficient modular homes have a direct impact on the utility bill costs. The reduction or even elimination of any heating and cooling systems leads to big reductions in energy use (electricity, gas and even water) [14]. Moreover, if we choose to include alternative energy sources to supply our own demands, we may achieve a Net-Zero energy-efficient home.

Improved comfort: A heat-efficient modular home is a guarantee of a comfortable environment indoors: maintaining a warm and stable temperature in winter and a cool feeling in summer.

Healthier environment: One of the main ingredients for a healthy home is good quality indoor air and energy-efficient modular homes tend to show improved air quality values in comparison with non-energy-efficient homes. These values are a result of reducing the need for heating and cooling systems. Moreover, the mechanized ventilation system also contributes to a healthier environment since it ensures a constant air renovation and maintains optimal levels of Oxygen, Humidity and Carbon Dioxide.

Environmentally friendly: One of the selfless benefits of an energy-efficient modular home is a lower environmental impact. Since the energy demands are highly reduced, the gas emissions and greenhouse effect are significantly lower than those emitted by a standard house.

References:

Passive Design and Active Building Strategies Sustainable https://www.sustainable.to/strategies
Indoor Temperature: Staying in the comfort zone Rockwool International A/S https://www.rockwool.com/group/about-us/our-thinking/indoor-comfort-health-and-safety/indoor-climate/indoor-temperature/
How well insulated are modular and manufactured homes? Preferred Homes https://preferredhomesmi.com/uncategorized/how-well-insulated-are-modular-and-manufactured-homes/
Update or Replace Windows Energy Saver, U.S. Department of Energy’s (DOE) consumer resource on saving energy and using renewable energy technologies at home. https://www.energy.gov/energysaver/update-or-replace-windows
About Passive House – What is a Passive House? Passive House Institute https://passivehouse.com/02_informations/01_whatisapassivehouse/01_whatisapassivehouse.htm
About Energy Star Energy Star® https://www.energystar.gov/about?s=mega
Sustainability. Responsible Design + Construction Method Homes® https://www.methodhomes.net/sustainable-design
What is a Heat Recovery Unit? Casals Ventilación Air Industrial, SLU https://www.casals.com/en/ventilation-tools/concepts/what-is-a-heat-recovery-unit/
Fixsen A. (July 7, 2020) How to design a Net-Zero Home Architectural Digest Magazine https://www.architecturaldigest.com/story/how-to-design-a-net-zero-home
Frequently Asked Questions – Sustainability. Does Plant do LEED certification, net zero or passive homes? Plant Prefab, Inc. https://www.plantprefab.com/faq
Green, D. (March 31, 2021) 14 Energy-Efficient Home Features to look for when House Hunting Homebuyer https://homebuyer.com/learn/energy-efficient-homes
ggarwal, V. (January 13, 2021) How to calculate solar panel payback period (ROI) Energysage https://news.energysage.com/understanding-your-solar-panel-payback-period/
Top 7 Benefits of Energy Efficient Homes Morningston Estates https://morningtonestates.com/blog/energy-efficient-homes-benefits/

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