Energy Design, Studies & Legislation

HVAC energy design - building envelope, load calculations, KENAK, ROI

Choosing the ideal heating and cooling system is not based on rules of thumb, but on strict mathematics, loss studies and legislative frameworks. In this section, we analyse the science behind HVAC.

Discover how the building envelope and insulation dictate the needs of your equipment. Explore KENAK requirements for new and existing buildings, Passive House (Passivhaus) standards and learn how to conduct a proper techno-economic analysis, calculating the payback period (ROI) before investing your money.

The Envelope, Insulation & Passive Buildings (Passivhaus)

A building functions as a living organism. The better it is "dressed", the less energy it needs to stay warm. Here we explain why installing expensive equipment in an uninsulated home is, practically, money thrown away.

The Relationship Between Insulation and HVAC.

The biggest renovation mistake. Why we NEVER install a heat pump in an uninsulated home with old single-glazed windows and how insulation reduces the size (and cost) of the machine.

What is a Passive Building (Passivhaus)?

The future of construction. Analysis of the 5 core principles (Super-insulation, No Thermal Bridges, Airtightness, Energy Windows, Heat Recovery) that drop consumption to zero.

Envelope infographic - insulation, Passivhaus, thermal bridges, airtightness

External Wall Insulation (ETICS) vs Internal Insulation.

How the choice of insulation affects the "thermal mass" of your building and how it completely changes how you should set the thermostat (24/7 or intermittently).

Windows & Energy-Rated Glazing.

What is the U-Value you see on window brochures? How the right glass traps warmth in winter (Solar G-value).

Thermal Bridges.

The "invisible" points (such as balconies, columns and ring beams) where energy silently escapes. How they are detected and structurally insulated.

Building Airtightness & Blower Door Test.

How we measure total air leaks in a new home's envelope and why a perfectly airtight building mandatorily requires a Mechanical Ventilation system.

Load Calculations (Heat Losses & Cooling Loads)

The mechanical engineering backbone of the installation. We leave behind rough "per square metre" calculations and see how the energy a space loses and gains is scientifically calculated.

Heat Loss Study (EN 12831 Standard).

The step-by-step process. How the engineer accurately calculates the required heating kW, taking into account materials, walls and air infiltrating the home.

Cooling Load Calculation (ASHRAE / Carrier).

Cooling is much harder than heating. Understand the difference between Sensible load (the temperature you feel) and Latent load (the humidity to be removed).

Load calculation infographic - heat losses, cooling loads, degree days

Degree Days & Climate Zones.

Greece does not have the same climate everywhere. How we objectively calculate, through Degree Days, how cold (or hot) your area is in order to make proper studies.

Internal Gains & Solar Radiation.

How the sun through the window, people, the oven and computers heat the house for free in winter, but dramatically increase cooling needs in summer.

The Oversizing Myth.

Why the "get a bigger machine to be safe" mentality is destructive. How oversized systems reduce comfort, wear out quickly and consume more.

KENAK, Energy Upgrades & Legislation

A survival guide through the bureaucracy. Energy performance is no longer optional but strictly legislated. What every owner and builder needs to know before starting a project.

What is KENAK (Building Energy Performance Regulation)?

The construction bible. What the law requires for minimum insulation, window and HVAC system specifications in new and renovated buildings.

Energy Performance Certificate (EPC).

Your home's "energy passport". How it is issued, how much it costs and which specific interventions (e.g. boiler replacement, solar) upgrade your property's energy class.

KENAK infographic - EPC, nZEB, energy inspection

nZEB Buildings (Nearly Zero Energy Buildings).

The new pan-European standard. What strict legislation requires for new building permits, practically mandating the use of Photovoltaics and Heat Pumps.

HVAC Installation Energy Inspections.

When the law mandates inspection of old boilers or large AC units in commercial spaces and what penalties are imposed.

Techno-Economic Analysis, Subsidies & ROI

Here the numbers speak. How much does each system really cost to run and when will you recoup your investment. Avoid "hidden costs" and take advantage of government programmes.

kWh Cost Calculation per Fuel.

Electricity, Natural Gas, Oil or Pellet? How to compare the real cost of a thermal kilowatt-hour, considering the different efficiency ratings of each machine.

"Exoikonomo" & "Anakainizo" Programmes.

Subsidy guide. Which HVAC systems (heat pumps, solar water heaters, fan coils) are funded, what are the income criteria and what are the most common pitfalls.

ROI infographic - kWh cost, subsidies, payback, LCC

Heat Pump Return on Investment (ROI).

Is it worth spending €8,000 on a heat pump? A realistic example comparing purchase cost with annual savings against oil, to see in how many years you get your money back.

Dynamic (Time-of-Use) Electricity Tariffs & Smart HVAC.

The new energy era. How to program your system (e.g. DHW production) to work automatically during the specific hours when electricity prices drop to a minimum.

LCC (Life Cycle Costing) in HVAC.

Why the "cheap" supermarket air conditioner will cost you triple over a decade. Calculating Acquisition Cost + Operating Cost + Maintenance Cost over time.

Main HVAC Guide

Return to the full heating-cooling guide for energy production, hydraulic networks, emission systems, ventilation and automation.

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